Method of threading a cold rolled strip

Abstract

The application discloses a cold-rolled strip steel threading method and belongs to the technical field of steel rolling process control. The method comprises the following steps: obtaining the thickness of the strip steel; when the thickness of the strip steel is greater than a set thickness, adjusting the inlet tension of a rolling mill and the rolling force, the work roll bending degree and the intermediate roll bending degree of F1, F2 and F3 racks to set values; and adjusting the strip head of the strip steel to thread through the F1, F2 and F3 racks in turn by point adjustment, so that the thickness of the strip head is reduced to the set thickness under the action of the rolling force of each rack; and adjusting the strip head to thread through the F4 and F5 racks of the rolling mill and the outlet pinch roll in turn by point adjustment until the strip head enters a coiler, the coiling tension is established after the strip steel is coiled for three turns, and the threading is completed. The method can reduce the thickness of the strip head of the strip steel to the set thickness under the action of the rolling force of each rack, ensure that the inner ring of the strip steel can form effective frictional force with the core shaft of the coiler after the strip steel is coiled by the coiler, smooth force tension is established, normal production of the rolling mill is ensured, and downtime is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of rolling process control technology, in particular to a cold-rolled strip steel threading method. BACKGROUND

[0002] In the production of high-strength thick specifications in modern cold continuous rolling mill, due to the high hardness and large thickness of the hot-rolled strip steel, in the threading process, after the core shaft curls the thick specification strip steel, the inner circle of the strip steel cannot generate effective friction with the core shaft, resulting in that the inner circle of the core shaft cannot be fully wrapped, and causing the slipping phenomenon between the core shaft and the strip steel in the process of establishing tension at the outlet of the rolling mill, so that the outlet tension cannot reach the set value. The rolling mill cannot meet the starting conditions, forcing the production line to be forced to stop.

[0003] Therefore, how to solve the problem that the existing cold-rolled thick specification strip steel cannot establish tension at the outlet in the process of threading the raw material plate is a problem that needs to be solved at present. SUMMARY

[0004] In view of the above problems, the present application is proposed to provide a cold-rolled strip steel threading method which overcomes the above problems or at least partially solves the above problems, which can reduce the thickness of the strip steel head to a set thickness under the rolling force of each stand, ensure that the inner circle of the strip steel can form effective friction with the coiling machine core shaft after the coiling machine curls the strip steel, smoothly build tension, ensure normal production of the rolling mill, and reduce downtime.

[0005] The present application provides a cold-rolled strip steel threading method, which comprises:

[0006] obtaining the thickness of the strip steel;

[0007] when the thickness of the strip steel is greater than a set thickness, adjusting the inlet tension of the rolling mill, and the rolling force, work roll bending degree and intermediate roll bending degree of F1, F2 and F3 stands to a set value;

[0008] jogging the head of the strip steel to thread through F1, F2 and F3 stands in turn, so that the thickness of the head of the strip steel is reduced to the set thickness under the rolling force of each stand;

[0009] jogging the head to thread through F4 and F5 stands of the rolling mill and outlet pinch rolls in turn until the head enters the coiling machine, and establishing coiling tension after the strip steel is coiled for three turns to complete the threading.

[0010] Optionally, when the thickness of the strip steel is greater than a set thickness, adjusting the inlet tension of the rolling mill, and the rolling force, work roll bending degree and intermediate roll bending degree of F1, F2 and F3 stands to a set value, comprises:

[0011] Adjusting the roll gap of the F1, F2 and F3 stands to a minimum rolling force state set by the system, and adjusting the entry tension roll tension of the rolling mill to 80-120 KN;

[0012] Adjusting the roll gap of the F1, F2 and F3 stands to a rolling force of 3-5 MN, and increasing the tension of the entry tension roll to 30-50 KN in the entry tension build-up state of the rolling mill, and adjusting the work roll bending degree of the F1, F2 and F3 stands to 10-15%, and the intermediate roll bending degree to 5-10%.

[0013] Optionally, the entry tension of the rolling mill is positively correlated with the thickness of the strip.

[0014] Optionally, the rolling force of the F1, F2 and F3 stands is positively correlated with the thickness of the strip.

[0015] Optionally, the intermediate roll bending degree of the F1, F2 and F3 stands is negatively correlated with the thickness of the strip.

[0016] Optionally, the jog adjustment is performed on the strip head to sequentially pass through the F1, F2 and F3 stands, so that the thickness of the strip head is reduced to the set thickness under the action of the rolling force of each stand, comprising:

[0017] Adjusting the roll gap of the F1, F2 and F3 stands to an open state, and adjusting the front and rear strip clamping positions of each stand to the strip passing position;

[0018] Passing the strip head to the middle line of the F1 stand roll gap, adjusting the strip head position to the outlet side Amm of the F1 stand roll gap, after adjusting the entry tension of the rolling mill and the rolling force, work roll bending degree and intermediate roll bending degree of the F1 stand to the set value, jog adjusting the strip head to a first position, so that the thickness of the strip head is reduced to a first thickness under the action of the rolling force of the F1 stand, wherein the first position is below the rear strip clamping of the F1 stand;

[0019] Passing the strip head to the middle line of the F2 stand roll gap, adjusting the strip head position to the outlet side Amm of the F2 stand roll gap, after adjusting the entry tension of the rolling mill and the rolling force, work roll bending degree and intermediate roll bending degree of the F2 stand to the set value, jog adjusting the strip head to a second position, so that the thickness of the strip head is reduced from the first thickness to a second thickness under the action of the rolling force of the F2 stand, wherein the second position is 200-300 mm away from the rear strip clamping of the F2 stand;

[0020] The strip head is threaded to the middle line of the F3 rack roller gap, the strip head position is adjusted to the outlet side Amm of the F3 rack roller gap, after the entry tension of the rolling mill and the rolling force, work roll bending degree and intermediate roll bending degree of the F3 rack are set, the strip head is jogged to the third position, and the thickness of the strip head is reduced from the second thickness to the set thickness under the action of the rolling force of the F3 rack, wherein the third position is the joint between the fixed threading guide plate and the rotating guide plate between the F3 rack and the F4 rack.

[0021] The Amm length part of the strip head is cut off, wherein 20≤A≤30.

[0022] Optionally, after the strip head reaches the first position, the second position and the third position, the threading method further comprises:

[0023] The entry tension is removed, the F1 rack roller gap is lifted to 16mm, the entry centering device is jogged, the centering device is adjusted, and the strip steel is adjusted to the no deviation state.

[0024] Optionally, before the strip steel is threaded, the threading method further comprises:

[0025] The strip head is processed, and the strip head is bent to a set angle, so that the strip head meets the requirements of entering the rolling mill during the threading process.

[0026] Optionally, the set angle is 5°-10°.

[0027] Optionally, the set thickness is 3.0-4.0mm.

[0028] The technical scheme provided in the embodiment of the application has at least the following technical effects or advantages:

[0029] The threading method of the cold-rolled strip steel provided by the embodiment of the application reduces the thickness of the strip head of the strip steel to the set thickness under the action of the rolling force of each rack by adjusting the entry tension of the rolling mill and the rolling force, work roll bending degree and intermediate roll bending degree of the F1, F2 and F3 racks to the set value when the thickness of the strip steel is greater than the set thickness, ensures that the inner circle of the strip steel can form effective friction force with the mandrel of the coiler after the coiler winds the strip steel, successfully builds the tension, ensures the normal production of the rolling mill, and reduces the downtime.

[0030] The above description is only a summary of the technical scheme of the application, in order to more clearly understand the technical means of the application, the content of the specification can be implemented, and in order to make the above and other purposes, characteristics and advantages of the application more obvious and easy to understand, the following specific embodiments of the application are described. BRIEF DESCRIPTION OF DRAWINGS

[0031] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments with reference made to the accompanying drawings. The drawings are for purposes of illustration only and are not intended to be limiting in accordance with the present application. Like reference numerals have been used wherever possible to denote like parts in the various figures.

[0032] In the drawings:

[0033] Figure 1 is a structural schematic diagram of a cold-rolling threading device provided by an embodiment of the present application;

[0034] Figure 2 is a flowchart of a cold-rolled steel threading method provided by an embodiment of the present application. DETAILED DESCRIPTION

[0035] To make the purposes, technical solutions and advantages of the present application clearer, the embodiments of the present application will be described in further detail below with reference to the accompanying drawings.

[0036] To better understand the present application, the applicable scenarios of the threading method provided by the present application are briefly described below.

[0037] Figure 1 is a structural schematic diagram of a cold-rolling threading device provided by an embodiment of the present application, as shown in Figure 1 the device includes a No. 2 exit loop (not shown in the figure), an entry tension roller 1, an entry steel strip clamping 2, a mill entry slitting shear 3, a centering device 4, an F1 rack front steel strip clamping 5, an F1 rack 6, an F1 rack rear steel strip clamping 7, an F2 rack 8, an F2 rack rear steel strip clamping 9, an F3 rack 10, an F3 rack rear steel strip clamping 11, an F4 rack 12, an F4 rack rear steel strip clamping 13, an F5 rack 14, an exit pinch roller 15 and a coiling machine 16 arranged in sequence.

[0038] Among them, the steel strip is stored in the No. 2 exit loop to ensure continuous production; the entry tension roller 1 is used to provide entry tension for the mill; the entry steel strip clamping 2 is used to press the steel strip during threading to prevent the position of the steel strip from changing under the action of the loop tension; the mill entry slitting shear 3 is used to shear the steel strip; the centering device 4 is used to adjust the steel strip to a no-deviation state; each rack is used to produce plastic deformation of the steel strip during production, and opens the roll gap during threading to allow the steel strip to pass smoothly; the front and rear steel strip clamping of each rack is used to press the steel strip to prevent the steel strip from shaking; the exit pinch roller 15 is used to send the steel strip into the coiling machine 16; and the coiling machine 16 is used to coil the steel strip.

[0039] Figure 2 is a flowchart of a cold-rolled steel threading method provided by an embodiment of the present application, as shown in Figure 2 the threading method includes:

[0040] Step S201, obtaining the thickness of the strip steel.

[0041] Step S202, when the thickness of the strip steel is greater than the set thickness, adjusting the entry tension of the rolling mill, and the rolling force, the work roll bending degree and the intermediate roll bending degree of the F1, F2 and F3 stands to the set values.

[0042] In the embodiment, the set thickness can be 3.0-4.0 mm. In other embodiments, the set thickness can also be set to other thicknesses according to the needs of the operator to ensure that after the coiler curls the strip steel, the inner circle of the strip steel can form an effective friction force with the coiler mandrel, and the build tension can be smooth, which is not limited by the present application.

[0043] Optionally, step S202 can include:

[0044] adjusting the roll gap state of the F1, F2 and F3 stands to the minimum rolling force state set by the system, and adjusting the entry tension roll tension of the rolling mill to 80-120 KN;

[0045] adjusting the roll gap of the F1, F2 and F3 stands to the rolling force to increase to 3-5 MN, increasing the tension of the entry tension roll to 30-50 KN in the entry tension build state of the rolling mill, and adjusting the work roll bending degree of the F1, F2 and F3 stands to 10-15%, and the intermediate roll bending degree to 5-10%.

[0046] That is, in the embodiment, the set value of the entry tension of the rolling mill can be 110-170 KN, the set value of the rolling force of the F1, F2 and F3 stands can be 3-5 MN, the set value of the work roll bending degree can be 10-15%, and the set value of the intermediate roll bending degree can be 5-10%.

[0047] For example, the minimum rolling force set by the F1, F2 and F3 stand system is usually 1.5 MN. The minimum rolling force is a reference state, and further increasing the rolling force of the stand on this reference is easier to adjust, otherwise it is easy to cause overpressure, and the minimum rolling force can only ensure that the two rolls are in a pressing state, and cannot make the strip steel thinner. At the same time, if the tension is increased in the minimum rolling force state, it will cause the strip steel to move backward, and further increasing the entry tension of the rolling mill is to prevent the strip steel from further deviating.

[0048] Optionally, the entry tension of the rolling mill is positively correlated with the thickness of the strip steel. That is, the thicker the thickness of the strip steel, the greater the entry tension of the rolling mill can be set within the set value range to prevent the strip steel from deviating.

[0049] Optionally, the rolling force of the F1, F2 and F3 stands is positively correlated with the thickness of the strip. That is, the thicker the thickness of the strip, the greater the rolling force of the F1, F2 and F3 stands can be set within a set value range, so as to ensure that the thickness of the strip head can be reduced to the set thickness under the action of the rolling force of each stand.

[0050] Optionally, the bending degree of the intermediate roll of the F1, F2 and F3 stands is negatively correlated with the thickness of the strip. That is, the thicker the thickness of the strip, the smaller the bending degree of the intermediate roll of the F1, F2 and F3 stands can be set within a set value range, so as to ensure that the strip has better flatness under the action of the rolling force, and prevent the strip from deviating during subsequent threading.

[0051] Step S203: The strip head is adjusted to pass through the F1, F2 and F3 stands in turn, so that the thickness of the strip head is reduced to the set thickness under the action of the rolling force of each stand.

[0052] Optionally, step S203 comprises:

[0053] The roll gap of the F1, F2 and F3 stands is adjusted to be in an open state, and the front and rear strip clamping positions of each stand are adjusted to be in a threading position.

[0054] The strip head is threaded to the middle line of the roll gap of the F1 stand, the position of the strip head is adjusted to be on the outlet side Amm of the roll gap of the F1 stand, the entry tension of the rolling mill and the rolling force, the bending degree of the work roll and the bending degree of the intermediate roll of the F1 stand are adjusted to be set values, the strip head is adjusted to a first position by a jog adjustment, and the thickness of the strip head is reduced to a first thickness under the action of the rolling force of the F1 stand, wherein the first position is below the rear strip clamping position of the F1 stand.

[0055] The strip head is threaded to the middle line of the roll gap of the F2 stand, the position of the strip head is adjusted to be on the outlet side Amm of the roll gap of the F2 stand, the entry tension of the rolling mill and the rolling force, the bending degree of the work roll and the bending degree of the intermediate roll of the F2 stand are adjusted to be set values, the strip head is adjusted to a second position by a jog adjustment, and the thickness of the strip head is reduced from the first thickness to a second thickness under the action of the rolling force of the F2 stand, wherein the second position is 200-300 mm away from the rear strip clamping position of the F2 stand.

[0056] The strip head is threaded to the middle line of the roll gap of the F3 stand, the position of the strip head is adjusted to be on the outlet side Amm of the roll gap of the F3 stand, the entry tension of the rolling mill and the rolling force, the bending degree of the work roll and the bending degree of the intermediate roll of the F3 stand are adjusted to be set values, the strip head is adjusted to a third position by a jog adjustment, and the thickness of the strip head is reduced from the second thickness to the set thickness under the action of the rolling force of the F3 stand, wherein the third position is the joint between the fixed threading guide plate and the rotating guide plate between the F3 stand and the F4 stand.

[0057] The length of the front Amm of the strip head is cut off, wherein 20≤A≤30.

[0058] By rolling of the three stands F1, F2, F3, the strip head is sequentially thinned to a set thickness, so that the core shaft and the strip can normally establish friction force after the strip head enters the coiler, and the outlet can be smoothly built up. In the above process, the Amm length part in front of the strip head is not passed through the stand rolling, and after the rolling is completed, the Amm length part in front of the strip head is cut off, so that the thickness of the strip head is more uniform, and there is no raw material thickness part (i.e. the part whose thickness exceeds the set thickness). In the embodiment, the Amm length part in front of the strip head can be cut off by using an electric shear, and the length of the remaining part of the strip head after being thinned by rolling of the rolling mill is 5-5.5 meters.

[0059] Optionally, after the strip head reaches the first position, the second position and the third position, the threading method further comprises:

[0060] The inlet tension is removed, the F1 stand roll gap is lifted to 16mm, the inlet centering device is jogged, the centering device is adjusted, and the strip is adjusted to a no-deviation state to prevent the strip from deviating during the curling process.

[0061] It should be noted that before rolling the strip head, the roll gap lubrication of each stand can be started, and the emulsion of each stand can be closed after the rolling is completed. The emulsion can cool, lubricate and preheat the roll, so that the surface of the strip head is kept in a good wet state, the intermetallic adhesion is prevented, and the calendering efficiency is improved.

[0062] Step S204, the strip head is sequentially threaded through the F4, F5 stands and the outlet pinch roll of the rolling mill, until the strip head enters the coiler, the coiling tension is established after the strip is coiled for three turns, and the threading is completed.

[0063] In the embodiment, the F4, F5 stand roll gaps can be adjusted to be in an open state, the front and rear strip clamping positions of each stand can be adjusted to be in a threading position, the outlet pinch roll can be adjusted to be in a closed state, the No. 2 outlet loop can be jogged to the outlet threading position core shaft, when the strip head reaches the outlet pinch roll, the outlet pinch roll is lifted, at this time, the strip is adjusted to be in a state that the coiler core shaft outer diameter is 630mm, the No. 2 outlet loop is continuously jogged, until the strip head enters the coiler, the coiling tension is established after the strip is coiled for three turns, and the threading is completed. At this time, the 5-5.5 meter strip head is thinned under the action of the rolling force of the F1-F3 stands, the friction force between the coiler core shaft and the strip can be normally established, and the outlet can be smoothly built up. The rolling mill returns to the rolling state, and the hot strip just starts to operate.

[0064] Optionally, before the strip is threaded, the threading method further comprises:

[0065] The strip head is treated to bend to a set angle, so that the strip head meets the requirements of entering the rolling mill during the threading process.

[0066] In the embodiment, the angle is set to 5°-10°. In other embodiments, the angle can also be other angles, and the present application does not limit this.

[0067] Specifically, the processing of the strip head can include:

[0068] The strip head is checked for no obvious inclusions, scabs, chromium marks and scratch defects within 5 meters, and no obvious wave shape. The strip head is adjusted to below the cutting shear at the mill inlet, and the cutting blade below the cutting shear is adjusted to the lifting state. A tool with a length of 2200 mm and a diameter of is placed below the strip between the strip clamping at the mill inlet and the cutting shear, and the ends of the tool are clamped on the two side columns of the cutting shear. The strip clamping at the mill inlet is operated from the highest position to the lowest position repeatedly for 3-5 times. Under the open state of the strip clamping, the strip head is adjusted to walk 150-200 mm in the direction of the mill outlet. The strip clamping at the mill inlet is continuously operated from the highest position to the lowest position repeatedly for 3-5 times to make the strip head produce small amplitude bending deformation. The tool is removed, and the cutting blade below the cutting shear is adjusted to the lowest position.

[0069] In order to better understand the present application, the following two specific examples are used to further illustrate the threading method of the present application.

[0070] I. Threading roll information: strip steel grade M4A06, yield strength 503 MPa, specification 5.5 mm*1520 mm. The specific threading method is as follows:

[0071] (1) Raw material strip head processing

[0072] The raw material strip head is checked for no obvious inclusions, scabs, chromium marks and scratch defects within 5 meters, and no obvious wave shape. The strip head is adjusted to below the cutting shear at the mill inlet, and the cutting blade below the cutting shear is adjusted to the lifting state. A tool with a length of 2200 mm and a diameter of is placed below the strip between the strip clamping at the mill inlet and the cutting shear, and the ends of the tool are clamped on the two side columns of the cutting shear. The strip clamping at the mill inlet is operated from the highest position to the lowest position repeatedly for 3-5 times. Under the open state of the strip clamping, the strip head is adjusted to walk 150-200 mm in the direction of the mill outlet. The strip clamping at the mill inlet is continuously operated from the highest position to the lowest position repeatedly for 3-5 times to make the strip head produce small amplitude bending deformation. The tool is removed, and the cutting blade below the cutting shear is adjusted to the lowest position.

[0073] (2) Rack operation

[0074] Adjust the F1-F5 stand roll gap to be in the open state, and the strip clamping position in front of and behind each stand to be in the threading position. Thread the strip head to the center line of the F1 stand roll gap, and adjust the strip head position to be 30 mm on the outlet side of the F1 stand roll gap. Adjust the F1 stand roll gap to be in the minimum rolling force state (1.5 MN) set by the system, and adjust the rolling mill inlet tension value to be 100 KN. Then establish the inlet tension. Continue to adjust the F1 stand roll gap to be in the 4.8 MN rolling force state. Increase the rolling mill inlet tension by 50 KN in the rolling mill inlet tension building state, so that the inlet tension reaches 150 KN. Adjust the F1 stand work roll bending degree to be 10%, and the intermediate roll bending degree to be 8%. Turn on the F1 stand work roll gap lubrication, and adjust the pressure to be 2.5 Bar. Group the No. 2 outlet loop, the inlet tension roller, and the F1 and F2 stands. Adjust the strip head to be below the F1 stand strip clamping. Remove the inlet tension, turn off the F1 stand emulsion, raise the F1 stand roll gap to be 16 mm, and jog the inlet centering device. Adjust the centering device, and adjust the strip to be in the no running off state.

[0075] Group the No. 2 outlet loop, the inlet tension roller, and the F1 and F2 stands. Send the strip head to the center line of the F2 stand roll gap, and adjust the strip head position to be 30 mm on the outlet side of the F2 stand roll gap. Adjust the F2 stand roll gap to be in the minimum rolling force state (1.5 MN) set by the system, and adjust the rolling mill inlet tension value to be 100 KN. Then establish the inlet tension. Continue to adjust the roll gap to be in the 4.5 MN rolling force state of the F2 stand. Increase the rolling mill inlet tension by 50 KN in the rolling mill inlet tension building state, so that the inlet tension reaches 150 KN. Adjust the F2 stand work roll bending degree to be 10%, and the intermediate roll bending degree to be 5%. Turn on the F2 stand work roll gap lubrication, and adjust the pressure to be 2.5 Bar. Group the No. 2 outlet loop, the inlet tension roller, and the F1 and F2 stands. Adjust the strip head to be 200 mm below the F2 stand strip clamping. Remove the inlet tension, turn off the F2 stand emulsion, raise the F2 stand roll gap to be 16 mm, jog the inlet centering device, and adjust the centering device. Make the strip return to the no running off state.

[0076] The exit loop, the entry tension roller, and the F1-F3 stands are set to point No. 2, and the strip head is sent to the middle line of the roller gap of the F3 stand. The position of the strip head is adjusted to be 30 mm on the exit side of the roller gap of the F3 stand. The roller gap state of the F3 stand is adjusted to the minimum rolling force state (1.5 MN) set by the system. The rolling mill entry tension value is adjusted to 100 KN, and then the entry tension is established. The roller gap is continuously adjusted to the rolling force of 4 MN of the F3 stand. The entry tension is increased by 50 KN under the tension building state of the rolling mill entry, so that the entry tension reaches 150 KN. The work roll bending degree of the F3 stand is adjusted to 10%, and the intermediate roll bending degree is 5%. The roller gap lubrication of the work roll of the F3 stand is turned on, and the pressure is adjusted to 2.5 Bar. The exit loop, the entry tension roller, and the F1-F3 stands are set to point No. 2, and the strip head is adjusted to the joint between the fixed strip guide and the rotating guide between the F3 stand and the F4 stand. The entry tension is removed, the emulsion of the F3 stand is turned off, the roller gap of the F3 stand is lifted to 16 mm, the entry centering device is set to point, and the centering device is adjusted to restore the strip steel to the non-deviation state. The first 30 mm length of the strip head is cut off by an electric scissors to ensure that the strip head has no original material thickness. The remaining 5-5.5 meters of the strip head is thinned by the rolling mill.

[0077] The exit pinch roll is adjusted to the closed state, the exit loop is set to point No. 2, and the exit pinch roll is lifted when the strip head reaches the exit pinch roll. At this time, the strip steel is adjusted to the state that the outer diameter of the coiler mandrel is 630 mm. The exit loop is continuously set to point No. 2 until the strip head enters the coiler. After the strip steel is coiled for three turns, the coiling tension is established, and the strip threading is completed. At this time, the 5-5.5 meters of the strip head is thinned under the action of the rolling force of the F1-F3 stands, the friction force between the coiler mandrel and the strip steel can be normally established, and the exit can be smoothly tensioned. The rolling mill returns to the rolling state, and the hot strip is started.

[0078] II. Threading information: the strip steel is 1CD61, the yield strength is 573 MPa, and the specification is 6.0 mm*1660 mm. The specific threading method is as follows:

[0079] (1) Raw material strip head treatment

[0080] It is checked that there is no obvious inclusion, scarring, chromium mark, and scratch defect within 5 meters of the raw material strip head, and there is no obvious wave shape. The strip steel synchronization signal is manually adjusted to the exit threading position coiler. The strip head is adjusted to be below the cutting blade of the entry cutting shear of the rolling mill. The cutting blade is lifted to the lifting state. The length of the strip head is 2200 mm, the diameter of the strip head is 6.0 mm, and the length of the strip head is 5-5.5 meters. The tool is put under the strip between the strip clamping device and the slitting shears of the mill entry, and the tool is clamped on the two upright columns on the two sides of the slitting shears. The strip clamping device of the mill entry is operated to fall from the highest position to the lowest position for 5 times. When the strip clamping device is opened, the strip head is adjusted to move 150-200 mm in the direction of the mill exit. The strip clamping device of the mill entry is continuously operated to fall from the highest position to the lowest position for 5 times, so that the strip head is bent and deformed slightly. The tool is removed, and the lower shear blade of the slitting shears is adjusted to the lowest position.

[0081] (2) Mill frame operation

[0082] The roll gaps of the F1-F5 mill frames are adjusted to be in the opened state, and the strip clamping devices before and after each mill frame are adjusted to be in the strip passing position. The strip head is passed to the middle line of the roll gap of the F1 mill frame, and the position of the strip head is adjusted to be 30 mm on the outlet side of the roll gap of the F1 mill frame. The roll gap state of the F1 mill frame is adjusted to be in the minimum rolling force state (1.5 MN) set by the system. The value of the mill entry tension is adjusted to be 100 KN, and then the entry tension is established. The roll gap of the F1 mill frame is continuously adjusted to be in the state of 4.8 MN of rolling force. The mill entry tension is increased by 50 KN in the state of the mill entry tension building, so that the entry tension reaches 150 KN. The bending degree of the work roll of the F1 mill frame is adjusted to be 10%, and the bending degree of the intermediate roll is adjusted to be 8%. The roll gap lubrication of the work roll of the F1 mill frame is started, the pressure is adjusted to be 2.5 Bar, the No. 2 exit loop, the entry tension roll, and the F1 mill frame are jogged, the strip head is adjusted to be under the strip clamping device of the F1 mill frame, the entry tension is removed, the emulsion of the F1 mill frame is turned off, the roll gap of the F1 mill frame is lifted to be 16 mm, the entry centering device is jogged, the centering device is adjusted, and the strip is adjusted to be in the state of no deviation.

[0083] The No. 2 exit loop, the entry tension roll, the F1 mill frame, and the F2 mill frame are jogged, the strip head is sent to the middle line of the roll gap of the F2 mill frame, and the position of the strip head is adjusted to be 30 mm on the outlet side of the roll gap of the F2 mill frame. The roll gap state of the F2 mill frame is adjusted to be in the minimum rolling force state (1.5 MN) set by the system. The value of the mill entry tension is adjusted to be 100 KN, and then the entry tension is established. The roll gap is continuously adjusted to be in the state of 4.5 MN of rolling force of the F2 mill frame. The mill entry tension is increased by 50 KN in the state of the mill entry tension building, so that the entry tension reaches 150 KN. The bending degree of the work roll of the F2 mill frame is adjusted to be 10%, and the bending degree of the intermediate roll is adjusted to be 5%. The roll gap lubrication of the work roll of the F2 mill frame is started, the pressure is adjusted to be 2.5 Bar, the No. 2 exit loop, the entry tension roll, the F1 mill frame, and the F2 mill frame are jogged, the strip head is adjusted to be 200 mm away from the strip clamping device of the F2 mill frame, the entry tension is removed, the emulsion of the F2 mill frame is turned off, the roll gap of the F2 mill frame is lifted to be 16 mm, the entry centering device is jogged, the centering device is adjusted, and the strip is restored to be in the state of no deviation.

[0084] The exit loop and the entry tension roller of the No. 2 point drive, the F1-F3 stands are set, the strip head is sent to the middle line of the roller gap of the F3 stand, the position of the strip head is adjusted to be 30mm on the exit side of the roller gap of the F3 stand, the roller gap state of the F3 stand is adjusted to the minimum rolling force state (1.5MN) set by the system, the entry tension value of the rolling mill is adjusted to 100KN, then the entry tension is established, the roller gap is continuously adjusted to the rolling force of 4MN of the F3 stand, the entry tension of the rolling mill is increased by 50KN under the entry tension building state of the rolling mill, so that the entry tension reaches 150KN, the bending degree of the work roll of the F3 stand is adjusted to 10% and the bending degree of the intermediate roll is adjusted to 5%, the roller gap lubrication of the work roll of the F3 stand is started, the pressure is adjusted to 2.5Bar, the exit loop of the No. 2 point drive, the entry tension roller and the F1-F3 stands are set, the strip head is adjusted to the joint between the fixed strip guide and the rotating guide between the F3 stand and the F4 stand, the entry tension is removed, the emulsion of the F3 stand is closed, the roller gap of the F3 stand is lifted to 16mm, the entry centering device is point driven, the centering device is adjusted, the strip steel is restored to the non-deviation state, the 30mm length part of the strip head in front is cut by an electric scissors, the strip head is ensured to have no raw material thickness part, and the remaining length of the strip head after the rolling and thinning of the strip head is 5-5.5m.

[0085] The exit pinch roll is adjusted to the closed state, the No. 2 exit loop is set to the exit strip feeding position mandrel, when the strip head reaches the exit pinch roll, the exit pinch roll is lifted, at this time, the strip steel is adjusted to the state that the outer diameter of the coiler mandrel is 630mm, the No. 2 exit loop is continuously set, the strip head enters the coiler, the coiling tension is established after the strip steel is coiled for three turns, and the strip feeding is completed. At this time, the 5-5.5m strip steel of the strip head is thinned under the action of the rolling force of the F1-F3 stands, the friction force between the coiler mandrel and the strip steel can be normally established, and the exit can be smoothly built. The rolling mill is restored to the rolling state, and the hot strip just after starting operation is performed.

[0086] The technical solutions in the embodiments of the present application have at least the following technical effects or advantages:

[0087] The strip feeding method of the cold strip steel provided by the embodiments of the present application adjusts the entry tension of the rolling mill and the rolling force, the bending degree of the work roll and the bending degree of the intermediate roll of the F1, F2 and F3 stands to the set values when the thickness of the strip steel is greater than the set thickness, so that the thickness of the strip head is reduced to the set thickness under the action of the rolling force of each stand, the inner circle of the strip steel can form effective friction force with the coiler mandrel after the strip steel is coiled on the coiler, the tension is smoothly built, the normal production of the rolling mill is ensured, and the downtime is reduced.

[0088] In the specification provided herein, a large number of specific details are described. However, it can be understood that the embodiments of the present application can be practiced without these specific details. In some examples, well-known methods, structures and techniques are not described in detail in order not to obscure the understanding of the present specification.

[0089] Similarly, it is to be understood that the embodiments of the application can include hardwired and / or program modules and that the various embodiments of the application can be implemented by computer, hardware, software, firmware, middleware, microcode and / or any combination of the above. To clearly illustrate this interchangeability of hardware and software, various embodiments of the application are described

[0090] It is to be understood that the embodiments of the application are not limited to the methods described above and that various modifications can be made without departing from the scope of the present application. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps other than those listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The application can be implemented by means of both hardware and software, and any combination thereof. In a unitary claim, several devices, apparatuses or means can be named by including their reference signs in the ordinal form, but the conjunction "and / or" can be understood separately from the respective reference signs. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. The single patent family members represent different inventive aspects of a single invention. The word "comprising" does not exclude the presence of elements or steps other than those listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The application can be implemented by means of both hardware and software, and any combination thereof. In a unitary claim, several devices, apparatuses or means can be named by including their reference signs in the ordinal form, but the conjunction "and / or" can be understood separately from the respective reference signs. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. The single patent family members represent different inventive aspects of a single invention.

Claims

1. A threading method of a cold-rolled strip, characterized by, The threading method comprises: acquiring the thickness of the strip steel; when the thickness of the strip steel is greater than a set thickness, adjusting the entry tension of the rolling mill and the rolling force, work roll bending degree and intermediate roll bending degree of F1, F2 and F3 stands to set values; jogging the strip head of the strip steel to thread through F1, F2 and F3 stands in sequence, so that the thickness of the strip head is reduced to the set thickness under the action of the rolling force of each stand; jogging the strip head to thread through F4 and F5 stands of the rolling mill and the exit pinch roll in sequence until the strip head enters the coiler, and establishing the coiling tension after the strip steel is coiled for three turns to complete the threading; when the thickness of the strip steel is greater than a set thickness, adjusting the entry tension of the rolling mill and the rolling force, work roll bending degree and intermediate roll bending degree of F1, F2 and F3 stands to set values, comprising: adjusting the roll gap state of F1, F2 and F3 stands to the minimum rolling force state set by the system, and adjusting the entry tension roll tension of the rolling mill to 80-120 KN; adjusting the roll gap of F1, F2 and F3 stands to the rolling force to increase to 3-5 MN, increasing the tension of the entry tension roll by 30-50 KN in the entry tension building state of the rolling mill, and adjusting the work roll bending degree of F1, F2 and F3 stands to 10-15% and the intermediate roll bending degree to 5-10%; jogging the strip head of the strip steel to thread through F1, F2 and F3 stands in sequence, so that the thickness of the strip head is reduced to the set thickness under the action of the rolling force of each stand, comprising: adjusting the roll gap of F1, F2 and F3 stands to the open state, and adjusting the strip steel clamping before and after each stand to the threading position; threading the strip head to the middle line of the roll gap of F1 stand, adjusting the position of the strip head to the outlet side Amm of the roll gap of F1 stand, and after the entry tension of the rolling mill and the rolling force, work roll bending degree and intermediate roll bending degree of F1 stand are adjusted to set values, jogging the strip head to the first position, so that the thickness of the strip head is reduced to the first thickness under the action of the rolling force of F1 stand, wherein the first position is below the strip steel clamping after F1 stand; threading the strip head to the middle line of the roll gap of F2 stand, adjusting the position of the strip head to the outlet side Amm of the roll gap of F2 stand, and after the entry tension of the rolling mill and the rolling force, work roll bending degree and intermediate roll bending degree of F2 stand are adjusted to set values, jogging the strip head to the second position, so that the thickness of the strip head is reduced to the second thickness from the first thickness under the action of the rolling force of F2 stand, wherein the second position is 200-300 mm away from the strip steel clamping after F2 stand; threading the strip head to the middle line of the roll gap of F3 stand, adjusting the position of the strip head to the outlet side Amm of the roll gap of F3 stand, and after the entry tension of the rolling mill and the rolling force, work roll bending degree and intermediate roll bending degree of F3 stand are adjusted to set values, jogging the strip head to the third position, so that the thickness of the strip head is reduced to the set thickness from the second thickness under the action of the rolling force of F3 stand, wherein the third position is the joint between the fixed threading guide plate and the rotating guide plate between F3 stand and F4 stand; The head front Amm length part is cut, wherein 20≤A≤30.

2. The strapping method of claim 1, wherein, The entry tension of the rolling mill is positively correlated with the thickness of the strip steel.

3. The method of claim 1, wherein, The rolling force of the F1, F2 and F3 stands is positively correlated with the thickness of the strip steel.

4. The method of claim 1, wherein, The intermediate roll bending roll of the F1, F2 and F3 stands is negatively correlated with the thickness of the strip steel.

5. The method of claim 1, wherein, After the strip head reaches the first position, the second position and the third position, the threading method further comprises: The entry tension is removed, the F1 stand roll gap is lifted to 16mm, the entry centering device is jogged, the centering device is adjusted, and the strip steel is adjusted to a non-deviation state.

6. The strapping method of claim 1, wherein, Before the strip steel is threaded, the threading method further comprises: The strip head is processed to bend to a set angle, so that the strip head meets the requirements of entering the rolling mill during threading.

7. The strapping method of claim 6, wherein, The set angle is 5°-10°.

8. The strapping method of claim 1, wherein, The set thickness is 3.0-4.0mm.

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