CN111001772A - Method and device for controlling roll gap under light pressing or heavy pressing - Google Patents
Method and device for controlling roll gap under light pressing or heavy pressing Download PDFInfo
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- CN111001772A CN111001772A CN201911345343.0A CN201911345343A CN111001772A CN 111001772 A CN111001772 A CN 111001772A CN 201911345343 A CN201911345343 A CN 201911345343A CN 111001772 A CN111001772 A CN 111001772A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/16—Controlling or regulating processes or operations
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
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- B22D11/1206—Accessories for subsequent treating or working cast stock in situ for plastic shaping of strands
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Abstract
The invention provides a method and a device for controlling a roll gap under light pressing or heavy pressing, which comprises the following steps: taking the roll gap value of the installed pressing device in the drawing as an initial roll gap value; calibrating the roll gap value of each pressing device by using a calibration block to obtain the corresponding relation between a displacement sensor and the roll gap value; when the pressing is not implemented, the pressing roller works in a hot blank pressure mode, and a roll gap value of the pressing device is obtained in real time through a displacement sensor; setting the relative rolling reduction of each rolling roller; when the pressing is carried out, the pressing roller carrying out the pressing works in a displacement control mode, the average value of the roll gap values of the pressing devices corresponding to the pressing roller when the pressing is not carried out for a set time is used as the reference roll gap value of the pressing devices, and the target roll gap value of the pressing device corresponding to the pressing roller is obtained according to the reference roll gap value and the relative pressing amount; and performing pressing roll gap control on the press-down roll by controlling the stroke of the displacement sensor according to the target roll gap value. The method and the device realize the dynamic measurement of the reference roll gap.
Description
Technical Field
The invention relates to the field of continuous casting, in particular to a method and a device for controlling a roll gap under light pressing or heavy pressing.
Background
The center segregation and the V-shaped segregation, namely the uneven composition of the central area of the casting blank, are inevitable products in the continuous casting solidification process, are main defects causing the internal quality problem of the billet continuous casting, and have great influence on the quality of the casting blank. In the subsequent treatment process of bearing steel, high-carbon hard wire, cord steel, gear steel and the like, the performances of a core and a matrix are inconsistent due to the reticular carbide, martensite structure, banded structure and the like generated by nonuniform center segregation components, and the problems of nonuniform hardness, drawing brittle fracture, wire breakage, unqualified flaw detection and the like are solved. The light/heavy reduction technique is the most effective way to improve and resolve center segregation.
As shown in fig. 1, a casting blank 1 passes through a crystallizer 2 and enters a reduction device 3, the reduction device comprises an upper roller 31 and a lower roller 32, and the light reduction/heavy reduction technology of the billet caster comprises one or more pairs of rollers, namely, at the solidification tail end zone of the casting blank, the casting blank is reduced by using a single roller or a plurality of rollers. Whether effective metallurgical effect can be achieved under light/heavy reduction or not is the core of the technology, namely the reduction position and the effective reduction, namely the effective deformation of the casting blank is achieved, and the effective control of the roll gap is the key to whether effective reduction can be implemented under light/heavy reduction or not.
The reduction of the casting blank by the roller is realized through an actual roller gap, and the reduction effect is influenced by the actual roller gap in the soft reduction/heavy reduction technology of the square billet continuous casting machine, namely the actual opening degree of a pair of rollers. The actual movement of the roll gap records the displacement through a displacement sensor of a hydraulic cylinder at the upper end of the pressing mechanism, and the movement of the hydraulic cylinder drives the upper roll to move up and down through the mechanism.
The displacement stroke range of the displacement sensor is 0-L, and the roll gap of the upper and lower rolls is the opening degree stroke L1-L2. The displacement travel range (0-L) of the displacement sensor and the roll gap of the upper and lower rolls, namely the opening degree travel (L)1-L2) The corresponding relation of (a) is linear, namely after a certain displacement of the displacement sensor corresponds to a certain roll gap value, the displacement stroke variation of the displacement sensor is equivalent to the roll gap variation, the linearity is ensured by a mechanism of the equipment, and the displacement input of the hydraulic cylinder and the output transfer function of the actual roll gap are linear.
In the prior art, the actual value of the roll gap can be accurately obtained only by measuring, in the roll gap calibration process, the hydraulic cylinder is controlled to move according to the difference △ between the set roll gap value and the initialized roll gap value, so that the value of the displacement sensor stays at the position corresponding to the set roll gap value, the actual value of the roll gap is measured, the corresponding relation between the roll gap and the displacement sensor is established according to the actual roll gap value which is the actual roll gap value measured by the roll gap, calibration is completed, and the actual position where the roll stays is controlled according to the set roll gap value due to the limited precision of initialization, so that the measured actual roll gap is different from the set roll gap.
In the case of performing soft reduction or heavy reduction, since the thickness of the cast slab before reduction is varied, it is necessary to measure the actual thickness of the cast slab before reduction to ensure effective reduction, and it is a conventional practice to set a measuring roll in front of the first roll or the first pair of rolls, and to set a reference roll gap by the measured thickness of the cast slab, so that the set reference roll gap is fixed during reduction. The control method of the absolute rolling reduction of the fixed reference roll gap needs the roll gap control precision of each pair of the press rolls to be high enough to meet the requirement, and can not eliminate the deviation of the system caused by clearance and deformation, so the fluctuation of the metallurgical effect is large.
The control precision is achieved by adopting a control method of the absolute rolling reduction of the fixed reference roll gap, the system is required to be calibrated and calibrated, the calibration and calibration are difficult to guarantee and realize due to the limitation of field conditions, and the calibration and calibration are attempted in the prior art.
The problems and the disadvantages of the prior art and the method are that the online measurement workload of the actual roll gap of the roller is large, and the manual measurement difficulty is large and even difficult to realize due to the narrow casting flow interval of the square billet. The initialization, calibration and calibration processes are too complex, the field production time is short, and the requirements of large-scale production are difficult to adapt. As a result, the roll gap control precision is poor, the reduction amount cannot be effectively realized, and the quality of the casting blank fluctuates.
In order to solve the above-mentioned drawbacks and problems in implementing the soft/heavy reduction roll gap control, the skilled person proposes different methods and solutions. Patent (CN106041010B) 'a calibration method for continuous casting bloom soft reduction' proposes a method for correcting calibration by combining cold calibration blocks and manual measurement, and a method for correcting compensation by hot billet reduction, which is used for soft reduction of bloom bearing steel and tries to compensate deviation caused by equipment deformation and casting blank deformation.
This method does not reduce the number of manual measurement steps, and the application is still limited. The roll gap control accuracy cannot be guaranteed.
In patent (CN104858358B), a method and a device for controlling soft reduction or heavy reduction based on a billet caster are provided, which omits the steps of cold initialization, calibration and the like, and directly uses a hot billet to perform calibration. Due to the unevenness of the casting blank, the accurate calibration of the roll gap cannot be realized.
Disclosure of Invention
The present invention has been made to solve the above-mentioned problems occurring in the prior art, and an object of the present invention is to provide a method and an apparatus for controlling a roll gap under a soft reduction or a hard reduction in which a reference roll gap is dynamically set.
According to one aspect of the invention, a roll gap control method under the condition of light pressing or heavy pressing of square billets is provided, and comprises the following steps:
initializing a roll gap, installing a pressing device according to a drawing, taking an upper roll of the pressing device as a lower pressing roll, stopping at the lowest position, and taking a roll gap value of the pressing device after installation in the drawing as an initial roll gap value;
calibrating the roll gap value, and calibrating the roll gap value of each pressing device by adopting a calibration block to obtain the corresponding relation between the displacement sensor of each pressing device and the roll gap value;
when the reduction is not implemented, each lower pressing roller works according to a hot billet pressure mode, and a roll gap value of a reduction device is obtained in real time through a displacement sensor, wherein the roll gap value is also the measured thickness of a casting blank for producing a square billet;
setting the relative rolling reduction of each rolling roller;
when the pressing is carried out, the pressing roller carrying out the pressing works in a displacement control mode, the average value of the roll gap values of the pressing devices corresponding to the pressing roller when the pressing is not carried out for a set time is used as the reference roll gap value of the pressing devices, and the target roll gap value of the pressing devices corresponding to the pressing roller is obtained according to the reference roll gap value and the relative pressing amount corresponding to the pressing roller;
and performing pressing roll gap control on the press-down roll by controlling the stroke of the displacement sensor according to the target roll gap value.
Preferably, the method further comprises the following steps:
taking the difference between the reference roll gap value corresponding to the first press roll and the target roll gap value corresponding to the last press roll as a first total reduction amount;
adding the relative rolling reduction of each rolling roller to obtain a second total rolling reduction;
judging whether the difference value of the first total pressure drop and the second total pressure drop is within a set deviation or not;
if the roll gap value is not within the set deviation, returning to the step of calibrating the roll gap value.
Preferably, the method further comprises the following steps:
setting the relative rolling reduction of each rolling roller in a list form;
setting a time period;
obtaining a roll gap value measured in a set time period through a corresponding relation between a displacement sensor and the roll gap value, taking an average value of the roll gap values measured in the previous time period of the pressing moment of the first press roll as a reference roll gap of a pressing device corresponding to the first press roll, and obtaining a target roll gap value of the pressing device corresponding to the first press roll according to the relative pressing amount of the first press roll;
the first press roller is pressed according to a target roll gap value of a pressing device corresponding to the first press roller, so that the thickness of the casting blank pressed by the first press roller is the target roll gap value;
obtaining the displacement of the casting blank from the first press roller to the second press roller in a time period according to the casting speed;
judging whether the displacement is not smaller than the roller distance between the first press-down roller and the second press-down roller;
if the distance is not less than the roller distance, repeating the pressing step of the first press-down roller, and pressing down the second press-down roller;
if the displacement is smaller than the roller spacing, prolonging the time period until the displacement is not smaller than the roller spacing;
the above-described pressing step of the first press roll is repeated until the last press roll performs the pressing.
Further, preferably, the method further comprises the following steps:
when the relative rolling reduction of the lower rolling rolls in the list is changed, the following steps are executed:
changing the previous reference roll gap value by adopting the relative reduction of the reference roll gap of the pressing device corresponding to the first press roll, obtaining a new target roll gap value according to the relative reduction in the new list, and executing pressing according to the new target roll gap value;
and the other press rolls sequentially obtain the target roll gap value of each press roll according to the thickness of the casting blank pressed by the previous press roll.
Furthermore, it is preferable that:
and when the roll number of the first press roll changes, taking the average value of the roll gap values of the new first press roll in a time period before the press moment as the reference roll gap of the press device corresponding to the new first press roll.
Preferably, the ratio of the length to the width of the cross section of the casting blank of the square billet is not more than 4.
According to another aspect of the present invention, there is provided a roll gap control device under light or heavy pressing, including:
the initialization module is used for initializing a roll gap, installing a pressing device according to a drawing, taking an upper roll of the pressing device as a lower pressing roll and stopping at the lowest position, and taking a roll gap value of the pressing device after installation in the drawing as an initial roll gap value;
the calibration module is used for calibrating the roll gap value, and calibrating the roll gap value of each pressing device by adopting the calibration block to obtain the corresponding relation between the displacement of the displacement sensor of each pressing device and the roll gap value;
the corresponding relation between the reading of the displacement sensor and the roll gap value is determined after calibration of a calibration module, and the actual roll gap value is obtained through the reading of the displacement sensor;
the mode setting module is used for setting the working mode of the press roller to be a hot blank pressure mode when the pressing is not carried out, and setting the working mode of the press roller to be a displacement control mode when the pressing is carried out;
the relative rolling reduction setting module is used for setting the relative rolling reduction of each rolling roller;
a reference roll gap value obtaining module, which takes the average value of roll gap values of the rolling device corresponding to the rolling roller when the rolling is not performed for a set time as the reference roll gap value of the rolling device, wherein the roll gap value is also the measured thickness of the casting blank;
the target roll gap value obtaining module is used for obtaining a target roll gap value of a pressing device corresponding to the pressing roller according to the reference roll gap value and the relative pressing amount corresponding to the pressing roller;
and the pressing module is used for controlling the pressing roll gap of the pressing roll by controlling the stroke of the displacement sensor according to the target roll gap value.
Preferably, the device further comprises a stability detection module for detecting the stability of the roll gap control under the light pressing or the heavy pressing of the square billet, and the stability detection module comprises:
a first total rolling reduction obtaining unit configured to obtain a first total rolling reduction by using a difference between a reference roll gap value corresponding to the first lower press roll and a target roll gap value corresponding to the last lower press roll;
a second total rolling reduction obtaining unit which adds the relative rolling reductions of the respective rolling rolls to obtain a second total rolling reduction;
and the judging unit is used for judging whether the difference value of the first total rolling reduction and the second total rolling reduction is within a set deviation, if so, the roll gap control of the pressing module meets the stability requirement, and if not, a signal is sent to the calibrating module to recalibrate the roll gap.
Preferably, the relative rolling reduction setting module sets the relative rolling reduction of each of the rolling rolls in a form of a list; the reference roll gap value obtaining module sets a time period, and obtains a roll gap value measured in the time period through the corresponding relation between the displacement sensor and the roll gap value.
Further, preferably, the method further comprises the following steps:
the counting module is used for counting the pre-pressed press roller;
the displacement obtaining module is used for obtaining the displacement of the casting blank between two adjacent press rolls in a time period according to the blank drawing speed;
and the judging module is used for judging whether the displacement of the casting blank obtained by the displacement obtaining module in two adjacent press rolls is not smaller than the roll distance between the two press rolls, if not, sending a signal to the counting module to obtain the next press roll to be subjected to pre-reduction, and performing the reduction on the next press roll to be subjected to the pre-reduction through the displacement sensor, the mode setting module, the relative reduction setting module, the reference roll gap value obtaining module, the target roll gap value obtaining module and the press module, if so, sending a signal to the reference roll gap value obtaining module to prolong the time period until the condition that the displacement of the two adjacent press rolls is not smaller than the roll distance between the two press rolls is met.
The method and the device for controlling the roll gap under the soft reduction or the heavy reduction adopt the drawing size without initializing the actual measured roll gap, adopt the calibration block for calibration, each calibrated roll can be used as a measuring roll under the hot billet reduction, measure the thickness of a casting blank in real time, adopt the method of independently measuring the thickness of the casting blank by each roll, combine the roll gap under the light/heavy reduction of the square billet, design uniformly, set the dynamic reference roll gap independently, calculate the target roll gap through the dynamic reference roll gap and the relative reduction to eliminate the problem of large fluctuation of metallurgical effect caused by the deviation generated by clearance and deformation, have high roll gap control precision, simple operation, reduced influence limited by field equipment and adaptation to production fields.
Drawings
Other objects and results of the present invention will become more apparent and more readily appreciated by reference to the following description and claims taken in conjunction with the accompanying drawings. In the drawings:
FIG. 1 is a schematic representation of a prior art billet caster under light or heavy reduction;
FIG. 2 is a flow chart of the roll gap control method under light or heavy pressing according to the present invention;
FIG. 3 is a schematic view of a slight or heavy reduction roll gap control method according to the present invention;
4-6 are schematic diagrams of automatic roll gap calibration of the roll gap control method under light pressing or heavy pressing according to the invention;
FIGS. 7-9 are schematic views of the billet light/heavy hold-down procedure according to the present invention;
FIG. 10 is a block diagram showing the structure of a roll gap control device for soft or heavy pressing according to the present invention.
In the drawings, the same reference numerals indicate similar or corresponding features or functions.
Detailed Description
In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more embodiments. It may be evident, however, that such embodiment(s) may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form in order to facilitate describing one or more embodiments.
Various embodiments according to the present invention will be described in detail below with reference to the accompanying drawings.
Fig. 2 is a flowchart of a roll gap control method under light or heavy pressing according to the present invention, and as shown in fig. 2, the roll gap control method under light or heavy pressing includes:
step S1, initializing a roll gap, installing the screw down device according to a drawing (a factory installation drawing of the screw down device, for example, a factory installation drawing of a tension leveler), taking an upper roll of the screw down device as a lower roll, stopping at the lowest position, and taking a roll gap value of the screw down device after installation in the drawing as an initial roll gap value;
step S2, calibrating the roll gap value, and calibrating the roll gap value of each screw-down device by adopting a calibration block to obtain the corresponding relation between the displacement sensor of the screw-down device and the roll gap value;
step S3, when the reduction is not carried out, each lower pressing roller works according to a hot billet pressure mode, a roll gap value of the reduction device is obtained in real time through a displacement sensor, the roll gap value is also the measured thickness of a casting blank for producing a square billet, the hot billet pressure mode is realized by driving an upper roller to reduce according to the set pressure through a hydraulic cylinder, and the position is stopped by the resistance of the lower support of the roller;
step S4, setting the relative rolling reduction of each rolling roller;
step S5, when the pressing is carried out, the pressing roller carrying out the pressing works according to a displacement control mode, the average value of the roll gap values of the pressing devices corresponding to the pressing roller when the pressing is not carried out for a set time is used as the reference roll gap value of the pressing devices, the target roll gap value of the pressing devices corresponding to the pressing roller is obtained according to the reference roll gap value and the relative pressing amount corresponding to the pressing roller, the displacement control mode is that one target roll gap is set, and the hydraulic cylinder moves according to the displacement set by the sensor;
and step S6, performing press-down roll gap control on the press-down roll by controlling the stroke of the displacement sensor according to the target roll gap value.
The method for controlling the roll gap under the light pressing or the heavy pressing comprises initialization, calibration, dynamic setting of the reference roll gap, calculation of the target roll gap through the dynamic reference roll gap and the relative pressing amount and the like, can realize dynamic measurement of the reference roll gap, and can realize accurate calibration of the roll gap.
In step S1, as shown in fig. 3, the displacement sensor 4 moves the recording cylinder 5 in the stroke range S (0-L) and the opening stroke G (L) which is the gap 6 between the upper and lower rolls1-L2),L1Is the lowest position of the roll gap, L2Is the highest roll gap. The initialization is to preliminarily establish the corresponding relation between the stop position of the displacement sensor and the roll gap of the upper and lower rolls, namely the specific opening value. The stroke range of the displacement sensor and the roll gap of the upper and lower rolls, namely the opening degree, are linear, and the roll gap of the upper and lower rolls can be calculated through the displacement sensor as long as a corresponding relation is established corresponding to one point. The initial roll gap is positioned at the lowest position where the lower pressing roll 7 stays after the pressing device is installed, namely the minimum roll gap of the upper and lower rolls, the lowest position of the lower pressing roll 7, namely the minimum roll gap is generally the static state of the pressing device, and the roll gap is measured according to the drawing without actually measuring the roll gap. The initialized system can realize the control of the roll gap through the movement of the hydraulic cylinder and calculate and display the roll gap.
In step S2, a calibration block 8, i.e., a gauge block with a standard thickness after being processed, is pressed against the calibration block between the upper and lower rolls according to a set hot blank pressure, the standard thickness of the calibration block is an actual roll gap value, and the calibration is completed by establishing a corresponding relationship of the sensors. The calibration block needs a certain pressure, eliminates the clearance error of the equipment and is closer to the working state under the actual light/heavy pressure. The standard thickness of the calibration block is determined, and automatic calibration can be realized.
Referring to fig. 4-6, the automatic roll gap calibration process under the soft reduction/heavy reduction of the square billet is performed. And designing a calibration rod for calibration, and sequentially operating the calibration blocks below the calibration rollers to calibrate.
And the calibrated roll pressing roller can calculate the actual roll gap through the reading of the sensor. In the pressure control mode, the device can be used as a measuring roller.
And each calibrated press roll can be used as a measuring roll under the hot billet reduction, so that the thickness of the casting blank is measured in real time.
In step S5, the reference roll gap is a definition of the roll gap in the depressing control, that is, the roll gap before the depressing operation is performed.
See fig. 4, the relationship between the rolling reference roll gap, the absolute rolling reduction and the relative rolling reduction is as follows:
gapt (target roll gap) ═ Gapb (reference roll gap) - Δ G (relative reduction)
Δ G (relative reduction) ═ Gapb (reference roll gap) -Gapt (target roll gap)
Total rolling Σ Δ G (absolute rolling reduction of the last press roller) ═ Δ G1(reduction) +. DELTA.G2(reduction). + Δ Gi(reduction).
Wherein i is the index of the lower roll, Δ GiThe total reduction Σ Δ G of the cast piece is the sum of the relative reductions of the respective rolls for the ith roll.
In a preferred embodiment of the present invention, as shown in FIGS. 7-9, the steps S3-S6 include:
the relative reduction of each of the rolls is set in the form of a table, as shown in Table 1 below, and the reduction of the billet by weight/weight is started by sequentially delivering the reduction of each pair of rolls, ai;
TABLE 1
Roll No. | No.1 | No.2 | No.3 | No.i |
Relative reduction amount Δ G (mm) | a1 | a2 | a3 | ai |
Absolute reduction amount sigma (mm) | ∑G1=a1 | ∑G2=a1+a2 | ∑G3=a1+a2+a3 | ∑Gi=a1+a2+a3+…+ai |
Roller spacing (mm) | D1 | D2 | D3 | Di |
Time difference(s) | t1 | t2 | t3 | ti |
Setting a time period;
the roll gap value measured in a set time period is obtained through the corresponding relation between the displacement sensor and the roll gap value, the average value of the roll gap values measured in the previous time period of the pressing time of the first press roller (No.1) is used as the reference roll gap of the pressing device corresponding to the first press roller, and the target roll gap value of the pressing device corresponding to the first press roller is obtained according to the relative pressing amount of the first press roller.
G1apt (target roll gap) G1apb (reference roll gap) - Δ G1(relative rolling reduction);
the first press roll is pressed down according to the target roll gap value of the pressing device corresponding to the first press roll as shown in FIG. 7 (FIG. 7 shows the relative pressing amount Δ G of No.1 roll1The process of delivering the No.1 roller to the No.2 roller after the No.1 roller is reduced) so that the thickness of the casting blank after being reduced by the first press roller is the target roll gap value;
obtaining the displacement of the casting blank from the first press roller to the second press roller in a time period according to the casting speed
D12=v1×Δt1+v2×Δt2+...+vn×Δtn
Wherein D is12A time period for the displacement of the first to the second press roll, the time period comprising n sampling periods, 1,2,3,4,. cndot.n sampling periods, vnDrawing speed, Δ t, for the nth sampling periodnThe time length of the nth sampling period;
judging whether the displacement is not smaller than the roller distance between the first press-down roller and the second press-down roller;
if not, as shown in FIG. 8 (FIG. 8 shows that the full reduction is completedThen, the respective press rolls are pressed down), the pressing step of the first press roll is repeated, and the second press roll is pressed down, wherein G2apt (target roll gap) G2apb (reference roll gap) - Δ G2(relative rolling reduction);
if the displacement is smaller than the roller spacing, prolonging the time period until the displacement is not smaller than the roller spacing;
the above-described pressing step of the first lower press roll is repeated until the last lower press roll performs the pressing, see fig. 9 (fig. 9 shows the relative pressing amounts of the respective lower press rolls).
Preferably, a measuring roller No. c may be provided before the first press-down roller, operating in a hot blank pressure mode, to assist the first press-down roller in measuring a reference roll gap of a pressing device corresponding to the first press-down roller, thereby preventing a large deviation of the reference roll gap.
In an alternative embodiment, when the reduction list is changed from table 1 to table 2, the cast slab to be reduced by pressing the following table 1 follows the cast slab in order from the time when the No.1 roll finishes reducing the table 1, and finishes reducing in order. The new reduction schedule was carried out starting from roll No.1, the basic roll gap of roll No.1 still being performed as the original basic roll gap, i.e. the basic roll gap measured for the thickness of the original undepressed cast slab.
And tracking and measuring the thickness of the casting blank after the No.2 roller is reduced according to the No.1 roller in the new reduction list 2, and analogizing the other rollers.
TABLE 2
Roll No. | No.1 | No.2 | No.3 | No.i |
Relative reduction amount Δ G (mm) | b1 | b2 | b3 | bi |
Absolute reduction amount sigma (mm) | b1 | b1+b2 | b1+b2+b3 | ∑=b1+b2+b3+…+bi |
Roller spacing (mm) | D1 | D2 | D3 | Di |
Time difference(s) | t1 | t2 | t3 | ti |
That is, when the relative pressing amount of the pressing roller in the list is changed, the following steps are performed:
changing the previous reference roll gap value by adopting the relative reduction of the reference roll gap of the pressing device corresponding to the first press roll, obtaining a new target roll gap value according to the relative reduction in the new list, and executing pressing according to the new target roll gap value;
and the other press rolls sequentially obtain the target roll gap value of each press roll according to the thickness of the casting blank pressed by the previous press roll.
In another alternative embodiment, when the roll number of the first press roll is changed, and when the roll number of the first press roll is changed, the average value of the roll gap values of the new first press roll in a time period before the pressing time is taken as the reference roll gap of the pressing device corresponding to the new first press roll, and as described above, when the new pressing list needs to change the pressing position, that is, the number of the starting press roll is changed, the control is performed in the newly started method, that is, the step of pressing the pressing list 1.
In one embodiment, FIG. 9 shows the relative reduction of the bottom rollers, the target gap G of the last pair of rollersiReference roll gap G between apt and No.1 roll1The difference apb is the absolute reduction Σ Δ G, i.e., the first total reduction. The second total pressure sigma delta G can be obtained by the relative delta G of the rollersiThe summation yields:
the second total pressure amount Σ Δ G ═ Δ G1(reduction) +. DELTA.G2(reduction). + Δ Gi(rolling reduction).
And comparing the total pressure drop sigma delta G obtained by the two methods, wherein the difference value is within the set deviation delta, namely, the stability detection is met. Otherwise, the calibration and the reference roll gap setting process are carried out again.
That is, step S6 is followed by the steps of:
taking the difference between the reference roll gap value corresponding to the first press roll and the target roll gap value corresponding to the last press roll as a first total reduction amount;
adding the relative rolling reduction of each rolling roller to obtain a second total rolling reduction;
judging whether the difference value of the first total pressure drop and the second total pressure drop is within a set deviation or not;
if the roll gap value is not within the set deviation, returning to the step of calibrating the roll gap value.
Fig. 10 is a block diagram showing the configuration of the roll gap control device under the light or heavy pressing according to the present invention, and as shown in fig. 10, the roll gap control device under the light or heavy pressing includes:
the initialization module 10 is used for initializing a roll gap, installing a screw-down device according to a drawing, taking an upper roll of the screw-down device as a lower roll, stopping at the lowest position, and taking a roll gap value of the screw-down device as an initial roll gap value after installation in the drawing;
the calibration module 20 is used for calibrating the roll gap value, and calibrating the roll gap value of each screw-down device by adopting a calibration block to obtain the corresponding relation between the displacement of the displacement sensor of the screw-down device and the roll gap value;
the corresponding relation between the reading of the displacement sensor and the roll gap value is determined after calibration of a calibration module, and the actual roll gap value is obtained through the reading of the displacement sensor;
a mode setting module 30, which sets the working mode of the press roller as a hot blank pressure mode when the pressing is not performed, and sets the working mode of the press roller as a displacement control mode when the pressing is performed;
a relative rolling reduction setting module 40 for setting the relative rolling reduction of each of the press rolls;
a reference roll gap value obtaining module 50, which takes an average value of roll gap values of the reduction devices corresponding to the reduction rolls when reduction is not performed for a set time as a reference roll gap value of the reduction devices, wherein the roll gap value is also the measured thickness of the casting blank;
a target roll gap value obtaining module 60, which obtains a target roll gap value of the pressing device corresponding to the pressing roller according to the reference roll gap value and the relative pressing amount corresponding to the pressing roller;
and the pressing module 70 is used for controlling the pressing roll gap of the pressing roll by controlling the stroke of the displacement sensor according to the target roll gap value.
In one embodiment, the relative rolling reduction setting module 40 sets the relative rolling reduction of each of the rolling rolls in a list form; the reference roll gap value obtaining module 50 sets a time period, and obtains a roll gap value measured in the time period through a corresponding relationship between the displacement sensor and the roll gap value.
Preferably, the method further comprises the following steps:
a counting module 80 for counting the number of the pre-pressing rolls;
a displacement obtaining module 90, which obtains the displacement of the casting blank between two adjacent press rolls in a time period according to the blank drawing speed;
the judging module 100 judges whether the displacement of the casting blank obtained by the displacement obtaining module in two adjacent press rolls is not smaller than the roll distance between the two press rolls, if not, sends a signal to the counting module to obtain the next press roll to be subjected to pre-execution pressing, and performs pressing on the next press roll to be subjected to pre-execution pressing through the displacement sensor, the mode setting module, the relative pressing amount setting module, the reference roll gap value obtaining module, the target roll gap value obtaining module and the pressing module, and if the displacement is smaller than the roll distance, sends a signal to the reference roll gap value obtaining module to prolong the time period.
In an alternative embodiment, a stability detection module 110 is further included for detecting the stability of the roll gap control under the light pressing or the heavy pressing of the billet, including:
a first total rolling reduction obtaining unit 111 that takes a difference between a reference roll gap value corresponding to the first lower press roll and a target roll gap value corresponding to the last lower press roll as a first total rolling reduction;
a second total rolling reduction obtaining unit 112 for adding the relative rolling reductions of the respective rolling rolls to obtain a second total rolling reduction;
and the judging unit 113 is used for judging whether the difference value between the first total rolling reduction and the second total rolling reduction is within a set deviation, if so, the roll gap control of the pressing module meets the stability requirement, and if not, a signal is sent to the calibration module to recalibrate the roll gap.
In each of the above embodiments, the ratio of the length to the width of the cross section of the cast slab of the billet is not more than 4.
In one embodiment of the invention, a billet with a cross section of 180X 180mm is produced, the production drawing speed is 1.5m/min, the production steel grade 77B is produced, the superheat degree is 30 ℃, and the total reduction is 12 mm. The rolling control is implemented according to the rolling seam control method under light pressing or heavy pressing, and the metallurgical effect of the center C segregation index of 1.08 is obtained.
While the foregoing disclosure shows illustrative embodiments of the invention, it should be noted that various changes and modifications could be made herein without departing from the scope of the invention as defined by the appended claims. The functions, steps and/or actions of the method claims in accordance with the inventive embodiments described herein need not be performed in any particular order. Furthermore, although elements of the invention may be described or claimed in the singular, the plural is contemplated unless limitation to the singular is explicitly stated.
Claims (10)
1. A roll gap control method under the condition of light pressing or heavy pressing of square billets is characterized by comprising the following steps:
initializing a roll gap, installing a pressing device according to a drawing, taking an upper roll of the pressing device as a lower pressing roll, stopping at the lowest position, and taking a roll gap value of the pressing device after installation in the drawing as an initial roll gap value;
calibrating the roll gap value, and calibrating the roll gap value of each pressing device by adopting a calibration block to obtain the corresponding relation between the displacement sensor of each pressing device and the roll gap value;
when the reduction is not implemented, each lower pressing roller works according to a hot billet pressure mode, and a roll gap value of a reduction device is obtained in real time through a displacement sensor, wherein the roll gap value is also the measured thickness of a casting blank for producing a square billet;
setting the relative rolling reduction of each rolling roller;
when the pressing is carried out, the pressing roller carrying out the pressing works in a displacement control mode, the average value of the roll gap values of the pressing devices corresponding to the pressing roller when the pressing is not carried out for a set time is used as the reference roll gap value of the pressing devices, and the target roll gap value of the pressing devices corresponding to the pressing roller is obtained according to the reference roll gap value and the relative pressing amount corresponding to the pressing roller;
and performing pressing roll gap control on the press-down roll by controlling the stroke of the displacement sensor according to the target roll gap value.
2. The method for controlling a roll gap under a light or heavy reduction of a billet according to claim 1, further comprising:
taking the difference between the reference roll gap value corresponding to the first press roll and the target roll gap value corresponding to the last press roll as a first total reduction amount;
adding the relative rolling reduction of each rolling roller to obtain a second total rolling reduction;
judging whether the difference value of the first total pressure drop and the second total pressure drop is within a set deviation or not;
if the roll gap value is not within the set deviation, returning to the step of calibrating the roll gap value.
3. The method for controlling a roll gap under light or heavy pressing according to claim 1, further comprising:
setting the relative rolling reduction of each rolling roller in a list form;
setting a time period;
obtaining a roll gap value measured in a set time period through a corresponding relation between a displacement sensor and the roll gap value, taking an average value of the roll gap values measured in the previous time period of the pressing moment of the first press roll as a reference roll gap of a pressing device corresponding to the first press roll, and obtaining a target roll gap value of the pressing device corresponding to the first press roll according to the relative pressing amount of the first press roll;
the first press roller is pressed according to a target roll gap value of a pressing device corresponding to the first press roller, so that the thickness of the casting blank pressed by the first press roller is the target roll gap value;
obtaining the displacement of the casting blank from the first press roller to the second press roller in a time period according to the casting speed;
judging whether the displacement is not smaller than the roller distance between the first press-down roller and the second press-down roller;
if the distance is not less than the roller distance, repeating the pressing step of the first press-down roller, and pressing down the second press-down roller;
if the displacement is smaller than the roller spacing, prolonging the time period until the displacement is not smaller than the roller spacing;
the above-described pressing step of the first press roll is repeated until the last press roll performs the pressing.
4. The slight or heavy reduction roll gap control method according to claim 3, further comprising:
when the relative rolling reduction of the lower rolling rolls in the list is changed, the following steps are executed:
changing the previous reference roll gap value by adopting the relative reduction of the reference roll gap of the pressing device corresponding to the first press roll, obtaining a new target roll gap value according to the relative reduction in the new list, and executing pressing according to the new target roll gap value;
and the other press rolls sequentially obtain the target roll gap value of each press roll according to the thickness of the casting blank pressed by the previous press roll.
5. The slight or heavy reduction roll gap control method according to claim 3, further comprising:
and when the roll number of the first press roll changes, taking the average value of the roll gap values of the new first press roll in a time period before the press moment as the reference roll gap of the press device corresponding to the new first press roll.
6. The method for controlling a roll gap under light or heavy reduction according to claim 1, wherein the ratio of the length to the width of the cross section of the cast slab of the billet is not more than 4.
7. A roll gap control device under light pressing or heavy pressing is characterized by comprising:
the initialization module is used for initializing a roll gap, installing a pressing device according to a drawing, taking an upper roll of the pressing device as a lower pressing roll and stopping at the lowest position, and taking a roll gap value of the pressing device after installation in the drawing as an initial roll gap value;
the calibration module is used for calibrating the roll gap value, and calibrating the roll gap value of each pressing device by adopting the calibration block to obtain the corresponding relation between the displacement of the displacement sensor of each pressing device and the roll gap value;
the corresponding relation between the reading of the displacement sensor and the roll gap value is determined after calibration of a calibration module, and the actual roll gap value is obtained through the reading of the displacement sensor;
the mode setting module is used for setting the working mode of the press roller to be a hot blank pressure mode when the pressing is not carried out, and setting the working mode of the press roller to be a displacement control mode when the pressing is carried out;
the relative rolling reduction setting module is used for setting the relative rolling reduction of each rolling roller;
a reference roll gap value obtaining module, which takes the average value of roll gap values of the rolling device corresponding to the rolling roller when the rolling is not performed for a set time as the reference roll gap value of the rolling device, wherein the roll gap value is also the measured thickness of the casting blank;
the target roll gap value obtaining module is used for obtaining a target roll gap value of a pressing device corresponding to the pressing roller according to the reference roll gap value and the relative pressing amount corresponding to the pressing roller;
and the pressing module is used for controlling the pressing roll gap of the pressing roll by controlling the stroke of the displacement sensor according to the target roll gap value.
8. The apparatus for controlling a roughing mill seam according to claim 7 further comprising a stability detecting module for detecting stability of the roughing mill seam control including:
a first total rolling reduction obtaining unit configured to obtain a first total rolling reduction by using a difference between a reference roll gap value corresponding to the first lower press roll and a target roll gap value corresponding to the last lower press roll;
a second total rolling reduction obtaining unit which adds the relative rolling reductions of the respective rolling rolls to obtain a second total rolling reduction;
and the judging unit is used for judging whether the difference value of the first total rolling reduction and the second total rolling reduction is within a set deviation, if so, the roll gap control of the pressing module meets the stability requirement, and if not, a signal is sent to the calibrating module to recalibrate the roll gap.
9. The soft or heavy reduction roller seam control device according to claim 7, wherein the relative reduction amount setting module sets the relative reduction amount of each of the reduction rollers in a list form; the reference roll gap value obtaining module sets a time period, and obtains a roll gap value measured in the time period through the corresponding relation between the displacement sensor and the roll gap value.
10. The soft or heavy reduction pinch roll gap control device of claim 9, further comprising:
the counting module is used for counting the pre-pressed press roller;
the displacement obtaining module is used for obtaining the displacement of the casting blank between two adjacent press rolls in a time period according to the blank drawing speed;
and the judging module is used for judging whether the displacement of the casting blank obtained by the displacement obtaining module in two adjacent press rolls is not smaller than the roll distance between the two press rolls, if not, sending a signal to the counting module to obtain the next press roll to be subjected to pre-reduction, and performing the reduction on the next press roll to be subjected to the pre-reduction through the displacement sensor, the mode setting module, the relative reduction setting module, the reference roll gap value obtaining module, the target roll gap value obtaining module and the press module, if so, sending a signal to the reference roll gap value obtaining module to prolong the time period until the condition that the displacement of the two adjacent press rolls is not smaller than the roll distance between the two press rolls is met.
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