阅读说明：本技术 板坯上下边角温降的控制方法及装置 (Method and device for controlling temperature drop of upper and lower corners of plate blank ) 是由 幸利军 于 2019-01-14 设计创作，主要内容包括：本发明公开了一种板坯上下边角温降的控制方法及装置,该方法包括步骤1：开始,抽钢；步骤2：下达板坯(2)的钢种和厚度；步骤3：判断是否容易产生边线缺陷,若是,执行步骤4,若否,入口下导向辊(31)和出口下导向辊(32)低位,转步骤7；步骤4：判断是否标准厚度,若是,执行步骤5,若否,入口下导向辊和出口下导向辊低位,转步骤7；步骤5：入口下导向辊、出口下导向辊提升,板坯中心线(26)高于模块中心线(16),对板坯进行不对称倒角或圆角；步骤6：板坯尾部通过定宽机后,入口下导向辊、出口下导向辊低位；步骤7：结束。本发明能通过在线调节板坯与模块的相对标高差,对板坯进行对称或非对称的倒角或圆角,减少边线缺陷。(The invention discloses a method and a device for controlling temperature drop of upper and lower corners of a slab, wherein the method comprises the following steps of 1: beginning to pump steel; step 2: the steel grade and the thickness of the plate blank (2) are achieved; and step 3: judging whether the edge line defect is easy to generate, if so, executing a step 4, otherwise, turning to a step 7, wherein the inlet lower guide roller (31) and the outlet lower guide roller (32) are at low positions; and 4, step 4: judging whether the thickness is standard or not, if so, executing the step 5, otherwise, turning to the step 7 when the inlet lower guide roller and the outlet lower guide roller are in low positions; and 5: the inlet lower guide roll and the outlet lower guide roll are lifted, the center line (26) of the plate blank is higher than the center line (16) of the module, and the plate blank is subjected to asymmetric chamfering or fillet; step 6: after the tail part of the plate blank passes through the width fixing machine, the inlet lower guide roller and the outlet lower guide roller are at a low position; and 7: and (6) ending. The invention can carry out symmetrical or asymmetrical chamfering or fillet on the slab by adjusting the relative elevation difference between the slab and the module on line, thereby reducing the edge line defect.)

1. A control device for temperature drop of upper and lower corners of a slab comprises a width fixing machine (3), wherein the slab (2) moves between two modules (1) through an inlet lower guide roller (31) and an outlet lower guide roller (32) of the width fixing machine (3);

the method is characterized in that: the inlet lower guide roll (31) is provided with an inlet lifting oil cylinder (33), the outlet lower guide roll (32) is provided with an outlet lifting oil cylinder (34), the inlet lower guide roll (31) is installed on the width fixing machine (3) through the inlet lifting oil cylinder (33) and can move up and down, and the outlet lower guide roll (32) is installed on the width fixing machine (3) through the outlet lifting oil cylinder (34) and can move up and down.

2. A method for controlling the temperature drop of the upper and lower corners of the slab according to claim 1, comprising: the method comprises the following steps:

step 1: the hot rolling process is started, the heating furnace performs steel drawing, the inlet lower guide roll (31) and the outlet lower guide roll (32) are at a low position, and the center line (26) of the plate blank is superposed with the center line (16) of the module;

step 2: the process machine gives the steel grade and the thickness of the plate blank (2) to the width fixing machine (3);

and step 3: the width fixing machine (3) judges whether the current slab (2) is a steel type which is easy to generate side line defects, if so, the step 4 is executed, if not, the inlet lower guide roller (31) and the outlet lower guide roller (32) are kept at a low position, and the step 7 is executed;

and 4, step 4: the width fixing machine (3) judges whether the current slab (2) is a slab with a standard thickness, if so, the step 5 is executed, if not, the inlet lower guide roller (31) and the outlet lower guide roller (32) are kept at a low position, and the step 7 is executed;

and 5: an inlet lifting oil cylinder (33) lifts an inlet lower guide roller (31), an outlet lifting oil cylinder (34) lifts an outlet lower guide roller (32) to enable the center line (26) of the slab to be higher than the center line (16) of the module, and the module (1) conducts asymmetric chamfering or fillet on the slab (2);

step 6: after the tail of the slab (2) passes through the width fixing machine (3), an inlet lifting oil cylinder (33) lowers an inlet lower guide roller (31) to a low position, an outlet lifting oil cylinder (34) lowers an outlet lower guide roller (32) to a low position, and a slab center line (26) is superposed with a module center line (16);

and 7: and finishing the hot rolling process.

3. The method for controlling the temperature drop of the upper and lower corners of the slab as claimed in claim 2, wherein: in the step 5, when the slab center line (26) is higher than the module center line (16), the relative elevation difference between the slab center line (26) and the module center line (16) is as follows: H1-H2= Δ T × wherein H1 is the relative elevation of the slab centerline (26); h2 is the relative elevation of the module centerline (16); delta T is the difference between the temperature drop of the rough rolling area and 150 ℃, and delta T = T-150, wherein T is the temperature drop of the rough rolling area; and X is a height difference coefficient.

4. The method for controlling the temperature drop of the upper and lower corners of the slab as claimed in claim 3, wherein: and the temperature drop T of the rough rolling area = the tapping temperature of the plate blank-the temperature of the last frame of the rough rolling of the plate blank.

5. The method for controlling the temperature drop of the upper and lower corners of the slab as claimed in claim 3 or 4, wherein: the value range of the temperature drop T of the rough rolling area is 150-210 ℃, the temperature is calculated according to 150 ℃ below 150 ℃, and the temperature is calculated according to 210 ℃ above 210 ℃.

6. The method for controlling the temperature drop of the upper and lower corners of the slab as claimed in claim 3, wherein: the value range of the height difference coefficient X is 0.15 to 0.35.

Technical Field

The invention relates to a hot rolling process and a device, in particular to a method and a device for controlling temperature drop of upper and lower corners of a slab.

Background

Referring to fig. 1, a sizing Press (sizing Press) is an apparatus for reducing the width of a slab 2 by knocking the side of the slab 2 during the forward movement of the strip in the direction of an arrow or stopping the forward movement for a certain distance by reciprocating a module 1 in the width direction of the slab 2. The width fixing machine can reduce the width specification of continuous casting, and can improve the width control precision and reduce the head and tail cutting loss by controlling the shape after side pressing.

Referring to fig. 2, the striking surface of the prior art module 1 is composed of several working surfaces 11, 12, 13, 14, 15, each of which is a flat surface. Referring to fig. 3, in actual production, it is found that the slab 2 is prone to edge defects 3. Referring to fig. 4, the corner portions of the slab 2 are generally right-angled 21, and the right-angled 21 cools at a much faster rate than the rest of the slab 2. Under the action of the plane of the module 1, the slab 2 is compressed in the thickness direction to generate wrinkles on the side surfaces, and then the wrinkles are pressed into the upper and lower surfaces of the slab 2 due to flattening and widening when entering the horizontal rolling, so that the edge defects 3 are formed.

At present, the method for solving the sideline defect is to chamfer the edge of the slab 2, Chinese utility model patent Z L201520145993.1 discloses a large chamfer width fixing machine module, a trapezoidal groove is arranged on one side of the working surface of the large chamfer width fixing machine module, the large chamfer of the slab can be effectively formed in the width reducing process of the slab by the width fixing machine, the dog bone defect is reduced, and the strip steel edge defect is reduced.

However, in use, after chamfering the slab, see fig. 5, 6 and 9, where fig. 5 is a large chamfer slab and fig. 6 is a rounded slab, the upper corners 22, 23 and lower corners 24, 25 of the slab 2 are symmetrical with respect to the slab center line 26. The elevation of the inlet lower guide roll 31 and the outlet lower guide roll 32 of the width fixing machine 3 in the prior art is fixed, the width fixing machine 3 is designed according to the slab with the standard thickness produced by the production line, and when the slab with the standard thickness is produced, the relative elevation difference between the module central line 16 and the slab central line 26 is zero, namely, the module central line 16 and the slab central line 26 are coincident. In the rolling and transporting processes of the slab 2, the heat dissipation conditions of the upper corners 22 and 23 are better than those of the lower corners 24 and 25, the temperature drop speed of the upper corners 22 and 23 is obviously higher than that of the lower corners 24 and 25, the edge line defects are greatly reduced but still cannot be avoided, and the edge line defects on the upper surface of the strip steel are obviously more than those on the lower surface.

In this case, the problem can be solved by further increasing the chamfer or fillet of the mold in the continuous casting process, but the contact area between the width setter module 1 and the slab 2 is increased and the main motor current of the width setter is increased after further increasing the chamfer or fillet of the module in the hot rolling process. That is, the size of the chamfer of the module is limited by the width fixing function and cannot be increased infinitely. In practical application, the continuous casting process using the chamfer and fillet crystallizer still has many problems, especially the online width adjustment of the crystallizer is difficult, and breakout accidents are easy to happen. In addition, many hot rolling lines have slab edge heating devices added to reduce the edge temperature drop, but the devices consume much power and are expensive.

The upper corners have better heat dissipation conditions than the lower corners during rolling and transportation of the slabs. Referring to fig. 7, the chamfer angle or the fillet of the upper corner is increased, and the chamfer angle or the fillet of the lower corner is reduced, so that the temperature drop of the upper corner can be reduced, and the sideline defects are further reduced. Referring to fig. 8, after the chamfer or fillet of the upper corner is increased and the chamfer or fillet of the lower corner is decreased, the component force of the slab to the module in the upward direction is greater than that in the downward direction. The long-term existence of the asymmetric component force can cause adverse effects on the mechanical structure of the width fixing machine. However, in actual production, only part of steel grades are easy to have edge line defects, and when steel grades without edge line defects are produced, the plate blank is symmetrically chamfered or rounded, so that adverse effects on the mechanical structure of the width fixing machine are reduced to the maximum extent.

Disclosure of Invention

The invention aims to provide a method and a device for controlling temperature drop of upper and lower corners of a slab, which can perform symmetrical or asymmetrical chamfering or fillet on the slab by adjusting the relative elevation difference between the slab and a module on line, thereby reducing the edge line defect.

The invention is realized by the following steps:

a control device for temperature drop of upper and lower corners of a slab comprises a width fixing machine, wherein the slab moves between two modules through an inlet lower guide roller and an outlet lower guide roller of the width fixing machine; the lower guide roll of entry be equipped with entry lift cylinder under the guide roll, export lift cylinder is equipped with under the guide roll of export, the guide roll is installed on the sizing machine and can reciprocate through entry lift cylinder under the entry, the guide roll is installed on the sizing machine and can reciprocate under the export through export lift cylinder.

A method for controlling temperature drop of upper and lower corners of a plate blank comprises the following steps:

step 1: the hot rolling process is started, the heating furnace pumps steel, the inlet lower guide roll and the outlet lower guide roll are at a low position, and the center line of the plate blank is superposed with the center line of the module;

step 2: the process machine gives steel grade and thickness of the plate blank to the fixed width machine;

and step 3: the width fixing machine judges whether the current plate blank is steel which is easy to generate side line defects, if so, the step 4 is executed, if not, the inlet lower guide roller and the outlet lower guide roller are kept at low positions, and the step 7 is switched to;

and 4, step 4: the width fixing machine judges whether the current plate blank is the plate blank with the standard thickness, if so, the step 5 is executed, if not, the step is executed, the inlet lower guide roller and the outlet lower guide roller are kept at the low position, and the step 7 is switched to;

and 5: the inlet lifting oil cylinder lifts the inlet lower guide roller, the outlet lifting oil cylinder lifts the outlet lower guide roller to enable the center line of the plate blank to be higher than the center line of the module, and the module performs asymmetric chamfering or fillet on the plate blank;

step 6: after the tail part of the slab passes through the width fixing machine, the inlet lifting oil cylinder lowers the inlet lower guide roller to a low position, the outlet lifting oil cylinder lowers the outlet lower guide roller to a low position, and the center line of the slab is superposed with the center line of the module;

and 7: and finishing the hot rolling process.

In the step 5, when the center line of the slab is higher than the center line of the module, the relative elevation difference between the center line of the slab and the center line of the module is as follows: H1-H2= Δ T × wherein H1 is the relative elevation of the slab centerline; h2 is the relative elevation of the module centerline; delta T is the difference between the temperature drop of the rough rolling area and 150 ℃, and delta T = T-150, wherein T is the temperature drop of the rough rolling area; and X is a height difference coefficient.

And the temperature drop T of the rough rolling area = the tapping temperature of the plate blank-the temperature of the last frame of the rough rolling of the plate blank.

The value range of the temperature drop T of the rough rolling area is 150-210 ℃, the temperature is calculated according to 150 ℃ below 150 ℃, and the temperature is calculated according to 210 ℃ above 210 ℃.

The value range of the height difference coefficient X is 0.15 to 0.35.

Compared with the prior art, the invention has the following beneficial effects:

1. the invention can effectively reduce the side line and burr defects: before the method is used, the degradation rejection rate of the sideline defects is 0.07 percent, and the degradation rejection rate of the burr defects is 0.07 percent. After the method is used, the sideline defect degradation scrapping rate is reduced to 0.05%, the burr defect degradation scrapping rate is reduced to 0.03%, and the total yield is improved.

2. The invention does not increase the contact area between the fixed width machine module and the plate blank and the load of the fixed width machine.

3. In the continuous casting process, after the asymmetric chamfering crystallizer is adopted to eliminate chamfering of the lower corner, the number of the corners of the plate blank is reduced from 8 to 4, and the method is favorable for controlling the continuous casting defects of the corner positions of the plate blank.

The invention can carry out symmetrical or asymmetrical chamfering or fillet on the slab by adjusting the relative elevation difference between the slab and the module on line when producing steel grades which are easy to generate sideline defects, flexibly controls the temperature drop difference of the upper and lower corners of the slab on the premise of reducing the influence on equipment as much as possible, further reduces the sideline defects, and is suitable for producing slabs with standard thickness.

Drawings

FIG. 1 is a schematic diagram of the operation of a prior art width setter module;

FIG. 2 is a cross-sectional view of a prior art width setter module;

FIG. 3 is a schematic view of an edge defect of a prior art slab;

FIG. 4 is a cross-sectional view of a prior art slab;

FIG. 5 is a cross-sectional view of a prior art symmetrical chamfer slab;

FIG. 6 is a cross-sectional view of a prior art symmetrical radiused slab;

FIG. 7 is a cross-sectional view of a prior art asymmetric chamfer slab;

FIG. 8 is a force component diagram of a prior art asymmetric chamfer slab pair module;

FIG. 9 is a cross-sectional view of a prior art deckle;

FIG. 10 is a sectional view of the control device for controlling the temperature drop of the upper and lower corners of the slab according to the present invention;

FIG. 11 is a schematic diagram showing the relative elevations of the slab and the modules during normal production by the device for controlling the temperature drop of the upper and lower corners of the slab according to the present invention;

FIG. 12 is a sectional view showing the lifting state of guide rollers of the apparatus for controlling the temperature drop of the upper and lower corners of a slab according to the present invention;

FIG. 13 is a schematic diagram showing the relative elevations of the slab and the modules during the lifting production by the control device for controlling the temperature drop of the upper and lower corners of the slab according to the present invention;

fig. 14 is a flow chart of the method for controlling the temperature drop of the upper and lower corners of the slab.

In the figure, 1 module, 16 module center lines, 2 slabs, 26 slab center lines, 3 sizing machines, 31 inlet lower wire rollers, 32 outlet lower guide rollers, 33 inlet lifting oil cylinders and 34 outlet lifting oil cylinders.

Detailed Description

The invention is further described with reference to the following figures and specific examples.

Referring to fig. 10 to 13, a device for controlling the temperature drop of the upper and lower corners of a slab comprises a width setter 3, an inlet lift cylinder 33 and an outlet lift cylinder 34, wherein the slab 2 moves between two modules 1 through an inlet lower guide roller 31 and an outlet lower guide roller 32; an inlet lifting oil cylinder 33 is arranged below the inlet lower guide roller 31, an outlet lifting oil cylinder 34 is arranged below the outlet lower guide roller 32, the inlet lower guide roller 31 is installed on the width fixing machine 3 through the inlet lifting oil cylinder 33 and can move up and down, and the outlet lower guide roller 32 is installed on the width fixing machine 3 through the outlet lifting oil cylinder 34 and can move up and down, so that the heights of the inlet lower guide roller 31 and the outlet lower guide roller 32 are adjusted to adjust the relative elevation of the slab 2.

Referring to fig. 10 to 14, a method for controlling temperature drop of upper and lower corners of a slab includes the following steps:

step 1: the hot rolling process begins and the furnace draws steel with the inlet lower guide roll 31 and the outlet lower guide roll 32 in the lower position and the slab centerline 26 coincident with the module centerline 16.

Step 2: the process machine transmits information such as the steel grade and the thickness of the slab 2 to the width setter 3.

And step 3: the width fixing machine 3 judges whether the current slab 2 is steel which is easy to generate side line defects, if so, the step 4 is executed, if not, the inlet lower guide roller 31 and the outlet lower guide roller 32 are kept at low positions, the module 1 carries out symmetrical chamfering or fillet on the slab 2, the adverse effect on the mechanical structure of the width fixing machine 3 is reduced to the maximum extent, at the moment, the relative elevation difference between the module central line 16 and the slab central line 26 is zero, namely, the module central line 16 and the slab central line 26 are overlapped, and the step 7 is carried out.

And 4, step 4: the width fixing machine 3 judges whether the current slab 2 is a slab with a standard thickness, if so, the step 5 is executed, if not, the step 7 is executed, the inlet lower guide roller 31 and the outlet lower guide roller 32 are kept at a low position, the module 1 carries out symmetrical chamfering or round angle on the slab 2, the adverse effect on the mechanical structure of the width fixing machine 3 is reduced to the maximum extent, at the moment, the relative elevation difference between the module central line 16 and the slab central line 26 is zero, namely, the module central line 16 and the slab central line 26 are overlapped, and the step 7 is switched to.

And 5: the inlet lifting oil cylinder 33 lifts the inlet lower guide roller 31, the outlet lifting oil cylinder 34 lifts the outlet lower guide roller 32, the center line 26 of the plate blank is higher than the center line 16 of the module, and the module 1 carries out asymmetric chamfering or fillet on the plate blank 2, so that the generation of side line defects is reduced.

The relative elevation of the slab 2 and the module 1 needs to be adjusted according to the temperature drop condition of the rough rolling area of different production lines, and when the slab center line 26 is higher than the module center line 16, the relative elevation difference between the slab center line 26 and the module center line 16 is as follows: H1-H2= Δ T × X.

Wherein H1 is the relative elevation of the slab centerline 26; h2 is the relative elevation of module centerline 16; delta T is the difference between the temperature drop of the rough rolling area and 150 ℃, delta T = T-150, T is the temperature drop of the rough rolling area (rough rolling area temperature drop = slab tapping temperature-temperature of the final frame of the rough rolling of the slab), and the value range of T is 150 ℃ to 210 ℃ because the average temperature drop of the rough rolling area of a general hot rolling production line is 150 ℃ to 210 ℃, the value range of T is calculated according to 150 ℃ when the temperature is lower than 150 ℃, and the value range of T is calculated according to 210 ℃ when the temperature is higher than 210 ℃; x is a standard height difference coefficient, X is empirical data obtained according to experiments, and the value range of X is 0.15-0.35.

Step 6: after the tail of the slab 2 passes through the width fixing machine 3, the inlet lifting oil cylinder 33 lowers the inlet lower guide roller 31 to a low position, the outlet lifting oil cylinder 34 lowers the outlet lower guide roller 32 to a low position, and the slab center line 26 is superposed with the module center line 16.

And 7: and finishing the hot rolling process.