CN114054700B

CN114054700B - Method and device for pressing round billet

Info

Publication number: CN114054700B
Application number: CN202111204032.XA
Authority: CN
Inventors: 祭程; 朱苗勇; 胡文广
Original assignee: Northeastern University China
Current assignee: Northeastern University China
Priority date: 2021-10-15
Filing date: 2021-10-15
Publication date: 2022-11-15
Anticipated expiration: 2041-10-15
Also published as: CN114054700A

Abstract

The application discloses a method and a device for pressing round billets, wherein the method comprises the following steps: the method comprises the following steps that (1) first withdrawal and straightening machines and second withdrawal and straightening machines are alternately arranged, wherein each first withdrawal and straightening machine comprises a pair of first press rolls which are oppositely arranged, each second withdrawal and straightening machine comprises a pair of second press rolls which are oppositely arranged, and the directions of the first press rolls and the second press rolls are mutually vertical; determining target rolling reduction R corresponding to the first rolling reduction roller and the second rolling reduction roller; and controlling the first press-lower roller and the second press-lower roller to perform pressing operation on the round billet according to the target pressing amount R. The method solves the problems that the circular blank pressing efficiency is low and cracks are easy to generate in the prior art.

Description

Method and device for pressing round billet

Technical Field

The application relates to the technical field of continuous casting processes, in particular to a pressing method and device for a round billet.

Background

In the existing continuous casting process, the traditional square billet and plate blank pressing scheme is applied to a round billet, the round billet pressing efficiency is very low, cracks can be generated on the surface and inside of the round billet, and the ovality of the round billet is increased, so that the round billet product is unqualified.

At present, research on the round billet under pressurization is less at home and abroad, and partial scholars research the round billet soft reduction process, for example, zhongmei Jingcheng Cao student does not utilize a finite element simulation means, simulates the traditional reduction process of the round billet, and obtains the conclusion that the round billet is not suitable for the reduction process; the Zhongzhu Saidili Wanguo et al propose a brand-new roller row design which gives consideration to the adoption of a soft reduction technology in a continuous casting machine for large square billets and large round billets, and solve the roller row problem of whether a withdrawal and straightening unit is grooved to a certain extent. Li Liang et al proposed a one-way, multi-pass extrusion round billet reduction method using flat rolls, alleviating the problem of ovality increase during round billet reduction.

Patent CN109622905B proposes a method for designing a convex roller with a high-order polynomial curve for a bloom continuous casting withdrawal and straightening machine, which adopts the high-order polynomial method to design the shape of the convex roller suitable for the bloom continuous casting withdrawal and straightening machine, can effectively control the continuous casting quality of a continuous casting bloom, and the smooth curve transition can effectively avoid surface cracks caused by stress concentration. The design method of the pressing convex roller is suitable for continuous casting of large square billets and is not suitable for continuous casting of round billets.

Patent CN106735026B proposes a single-point and continuous heavy reduction process at the solidification end of a continuous casting slab. A press roll with large reduction is arranged in the sector section to achieve the effect of transferring the strain to the core of the casting blank; and a press roll with continuous small reduction is adopted to continuously press the blank after the sector section, so that the blank does not rebound after being pressed, and the pressing effect is further ensured. The proposal is suitable for square billets and plate blanks, and the problem of increasing the ovality of round billets can not be avoided if the proposal is used for continuously casting round billets.

Patent CN107008874B proposes a control method for the pressing down of the solidification end of a continuous casting billet in the unsteady state casting process, which solves the problem of the heavy pressing down of the solidification end of the continuous casting billet in the unsteady state casting process, and realizes the heavy pressing down effect of the solidification end in the unsteady state casting process, but the patent does not relate to a round billet pressing down scheme.

Patent CN104001891B provides an on-line control method for dynamic soft pressing and heavy pressing of small square billets. The method described in the scheme is applicable to small square billets and not to round billets. And the scheme adopts a flat roller and continuous casting billet extrusion method in the up-down direction, and is not suitable for round billets.

The patent CN108067501B provides a method for designing a working roll curve of a rolling mill under high temperature and high pressure aiming at a large square billet and a rectangular billet. The working roll optimally combines the flange roll shape and the box hole shape, optimally designs the geometric characteristics of the working roll, and further improves the three-way pressing effect of the deformation permeation of the core part of the casting blank and the central shrinkage cavity by applying the working roll in the rolling process under high temperature and high pressure. The scheme is suitable for high-temperature large square billets and rectangular billets and is not suitable for the shape characteristics of continuous casting round billets. And the scheme is single-pass rolling and is not suitable for the continuous casting reduction process.

Disclosure of Invention

In view of this, the present application provides a method and an apparatus for pressing a round billet, in which a plurality of pairs of arc-shaped press rollers are alternately arranged and have vertical directions, and the round billet is pressed in an up-down direction and a left-right direction alternately to obtain a round product, so that the ovality of the round billet can be reduced, and the pressing effect of the round billet can be ensured.

According to an aspect of the present application, there is provided a round billet rolling method, including:

alternately arranging a first withdrawal and straightening machine and a second withdrawal and straightening machine, wherein each first withdrawal and straightening machine comprises a pair of first press rollers which are oppositely arranged, each second withdrawal and straightening machine comprises a pair of second press rollers which are oppositely arranged, the directions of the first press rollers and the second press rollers are mutually vertical, and a first target shape parameter of each first press roller is the same as a second target shape parameter of each second press roller;

determining a target rolling reduction R corresponding to the first rolling press roller and the second rolling press roller;

and controlling the first press-lower roller and the second press-lower roller to perform pressing operation on the round billet according to the target pressing amount R.

Optionally, before the controlling the first and second platen rollers to perform the pressing operation, the method further comprises:

determining the first target shape parameter and the second target shape parameter, wherein the first target shape parameter comprises a minor half axis parameter and a major half axis parameter.

Optionally, the determining the target reduction R corresponding to the first and second rolling press rolls specifically includes:

determining the green compaction force corresponding to each rolling reduction in a plurality of preset rolling reductions;

the maximum reduction amount is selected as the target reduction amount R among green compaction forces less than or equal to a safe green compaction force.

Optionally, the determining the green compaction force corresponding to each reduction specifically includes:

determining the position of the central solid phase rate of the round billet to be 1 as a pressing position;

and respectively determining the green compaction force corresponding to each reduction when the pressing operation is performed at the pressing position according to each reduction.

Optionally, the determining a first target shape parameter of the first press roll and a second target shape parameter of the second press roll specifically includes:

obtaining the diameter d of the round billet;

calculating to obtain a first shape parameter according to the diameter d of the round billet and the target rolling reduction R, wherein the first shape parameter comprises a first minor semi-axis parameter a and a first major semi-axis parameter b;

taking the diameters of the round billets as a second minor half shaft parameter and a second major half shaft parameter of a second shape parameter respectively;

setting at least one third shape parameter, wherein a third minor semi-axis of the third shape parameter is greater than the first minor semi-axis parameter and less than the second minor semi-axis parameter, and a third major semi-axis of the third shape parameter is less than the first major semi-axis parameter and greater than the second major semi-axis parameter;

selecting the first target shape parameter among the first shape parameter, the second shape parameter, and the at least one third shape parameter.

Optionally, the calculating, according to the diameter d of the round billet and the target rolling reduction R, to obtain a first shape parameter specifically includes:

a＝d-R，

optionally, the selecting the first target shape parameter from the first shape parameter, the second shape parameter, and the at least one third shape parameter specifically includes:

determining each of the first shape parameter, the second shape parameter and the third shape parameter as a first to-be-selected shape parameter;

determining a surface strain value and a surface strain concentration of the round billet when the pressing operation is performed at each of the first parameters to be selected;

taking a first parameter to be selected corresponding to the surface strain value as a second parameter to be selected under the condition that the surface strain value is smaller than a surface strain threshold and the surface strain concentration is smaller than a concentration threshold;

determining a central strain value of the round billet when each second parameter to be selected is used for executing the pressing operation;

and comparing the central strain value, and taking the second parameter to be selected corresponding to the maximum central strain value as the first target shape parameter.

Optionally, an arithmetic progression relationship is formed among the first minor semi-axis parameter, the at least one third minor semi-axis parameter and the second minor semi-axis parameter;

the first long semi-axis parameter, the at least one third long semi-axis parameter and the second long semi-axis parameter are in an arithmetic progression relationship;

wherein the number of the third shape parameters is two.

Optionally, the alternately arranging the first withdrawal and straightening machine and the second withdrawal and straightening machine specifically includes:

determining the position with the central solid phase ratio of 0.3 of the circular blank as an initial position and the position with the central solid phase ratio of 1 of the circular blank as an end position;

and arranging one first withdrawal and straightening machine at the starting position, one second withdrawal and straightening machine at the ending position, and arranging other first withdrawal and straightening machines and other second withdrawal and straightening machines between the starting position and the ending position alternately.

According to another aspect of the present application, there is provided a round billet screw-down apparatus comprising:

the device comprises a first withdrawal and straightening machine and a second withdrawal and straightening machine, wherein the first withdrawal and straightening machine and the second withdrawal and straightening machine are alternately arranged, each first withdrawal and straightening machine comprises a pair of oppositely arranged first press rolls, each second withdrawal and straightening machine comprises a pair of oppositely arranged second press rolls, the directions of the first press rolls and the second press rolls are perpendicular to each other, and a first target shape parameter of each first press roll is the same as a second target shape parameter of each second press roll;

the determining module is used for determining target rolling reduction R corresponding to the first rolling press roller and the second rolling press roller;

and the control module is used for controlling the first press-lower roller and the second press-lower roller to perform pressing operation on the round billet according to the target pressing amount R.

Optionally, the device can realize the round billet pressing method.

By means of the technical scheme, the pressing method and device of the round billet are suitable for cylindrical billets. The round blanks are alternately pressed in the up-down direction and the left-right direction through a plurality of pairs of arc-shaped press rollers which are alternately arranged and are vertical to each other, so that a round product is obtained. When the continuous casting round billet is subjected to the pressing process, the increase of the ovality of the round billet after the pressing process can be effectively controlled, and the round billet is pressed on the premise of keeping the shape stability of the round billet. Aiming at the pressing operation of the round billet, the method that the arc-shaped first press-down roller and the arc-shaped second press-down roller are alternately arranged is adopted, the problems that the ovality of a finished product is too large and the shape of the finished product does not meet the requirement of a round shape in the traditional process are solved, and the pressing effect is effectively improved.

The above description is only an overview of the technical solutions of the present application, and the present application may be implemented in accordance with the content of the description so as to make the technical means of the present application more clearly understood, and the detailed description of the present application will be given below in order to make the above and other objects, features, and advantages of the present application more clearly understood.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application and not to limit the application. In the drawings:

fig. 1 is a schematic flow chart illustrating a circular blank pressing method provided by an embodiment of the present application;

FIG. 2 is a process diagram illustrating another round billet reduction method provided by an embodiment of the present application;

fig. 3 is a perspective view of a first rolling roller of another round billet rolling method according to an embodiment of the present application;

fig. 4 is a front view of a first reduction roller of another reduction method of a round billet according to an embodiment of the present application;

fig. 5 shows a schematic structural diagram of a pressing device for a round billet provided by an embodiment of the application.

Detailed Description

The present application will be described in detail below with reference to the accompanying drawings in conjunction with embodiments. It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.

In this embodiment, a method for pressing a round billet is provided, as shown in fig. 1, the method includes:

101, alternately arranging first withdrawal and straightening machines and second withdrawal and straightening machines, wherein each first withdrawal and straightening machine comprises a pair of first press rolls arranged oppositely, each second withdrawal and straightening machine comprises a pair of second press rolls arranged oppositely, the directions of the first press rolls and the second press rolls are mutually vertical, and the first target shape parameters of the first press rolls are the same as the second target shape parameters of the second press rolls;

the round billet pressing method provided by the embodiment of the application is mainly used for solving the problem that square billet and plate blank pressing schemes in the prior art are not suitable for round billets. Therefore, in the step 101, the first withdrawal and straightening machine 510 and the second withdrawal and straightening machine 520 are alternately arranged, wherein the first press roll 210 of the first withdrawal and straightening machine 510 and the second press roll 220 of the second withdrawal and straightening machine 520 are both arc-shaped, and the directions of the first press roll 210 and the second press roll 220 are perpendicular to each other, so that the round billet can be pressed at the first press roll 210 to be oval-shaped, and then the second press roll 220 is subjected to a compaction force perpendicular to the first press roll 210, so as to reduce the ovality of the round billet, and make the shape of the round billet more conform to the requirement of the round shape.

The second target shape parameter of the second press lower roll 220 is the same as the first target shape parameter of the first press lower roll 210, so that it is not necessary to provide two press lower rolls of different shapes, and the production cost is reduced.

Further, as shown in fig. 2, the first press-down roller 210 may be in an up-down direction, and the second press-down roller 220 may be in a left-right direction. At the moment, the withdrawal and straightening machine adopts a pressing mode that upper and lower pressed compacts and left and right pressed compacts are arranged in a staggered mode along the withdrawal direction. After the pair of press rolls are pressed in the vertical direction or the left-right direction, the press rolls are pressed in the direction vertical to the previous time, so that the ovality generated by the extrusion of the round billet by the pair of press rolls can be effectively improved, and the round billet is pressed in the vertical direction and the left-right direction alternately to obtain a round product.

Of course, the first and second

pressing rollers

210 and 220 may have other directions, and are not limited herein.

102, determining target rolling reduction R corresponding to the first rolling press roller and the second rolling press roller;

and 103, controlling the first press-lower roller and the second press-lower roller to perform press-down operation on the round billet according to the target press-down amount R.

In this embodiment, in order to achieve a better pressing effect, target pressing amounts corresponding to the first and second

pressing rollers

210 and 220 may be set, and the first and second

pressing rollers

210 and 220 may be controlled to perform the pressing operation according to the target pressing amounts.

By applying the technical scheme of the embodiment, the plurality of pairs of arc-shaped press rolls are alternately arranged and are vertical to each other, and the round billets are alternately pressed in the mutually vertical directions to obtain round products. When the continuous casting round billet is subjected to the pressing process, the increase of the ovality of the round billet after the pressing process can be effectively controlled, and the round billet is pressed on the premise of keeping the shape stability of the round billet. Aiming at the pressing operation of the round billet, the embodiment adopts the method that the arc-shaped first press-down roller 210 and the arc-shaped second press-down roller 220 are alternately arranged, so that the problems that the ovality of a finished product is too large and the shape does not meet the circular requirement in the traditional process are avoided, and the pressing effect is effectively improved.

Further, as a refinement and expansion of the specific implementation of the above embodiment, in order to fully illustrate the specific implementation process of the embodiment, another round billet pressing method is provided, which includes:

step 301, determining a position with a circular blank center solid phase ratio of 0.3 as a starting position and a position with a circular blank center solid phase ratio of 1 as an ending position;

specifically, in the case of drawing, the farther the round billet is drawn, the closer to the solidification state, that is, the different lengths of the round billet in the drawing direction, the different solid phase ratios thereof because the time taken to draw is long. Therefore, the solid fraction of the center position of the round billet at different lengths in the drawing direction, that is, the solid fraction of each point on the axis of the cylindrical round billet can be determined according to the continuous casting round billet solidification heat transfer two-dimensional slice model, and the position with the solid fraction of 0.3 is found as the starting position, and the position with the solid fraction of 1 is found as the ending position. Wherein the position with the solid phase ratio of 1 is the position where the round billet is just solidified.

Specifically, the parameters of the continuous casting round billet solidification heat transfer two-dimensional slice model comprise a steel type solid-liquid phase line, a heat exchange coefficient, specific heat and solidification latent heat steel type information, round billet section size, casting superheat degree, casting speed, length of each cooling zone and water continuous casting production parameters.

Furthermore, the temperatures of the round billet two-dimensional slices corresponding to different times can be extracted, and model parameters are adjusted and calibrated by comparing with the actual temperature on site.

Of course, a position having a solid phase ratio of another value may be used as the start position or the end position, and is not limited thereto.

302, arranging a first withdrawal and straightening machine at a starting position, arranging a second withdrawal and straightening machine at an ending position, and alternately arranging other first withdrawal and straightening machines and other second withdrawal and straightening machines between the starting position and the ending position, wherein each first withdrawal and straightening machine comprises a pair of first press rolls arranged oppositely, each second withdrawal and straightening machine comprises a pair of second press rolls arranged oppositely, and the directions of the first press rolls and the second press rolls are perpendicular to each other;

specifically, the first withdrawal and straightening unit 510 and the second withdrawal and straightening unit 520 are alternately arranged between the start position and the end position. During the withdrawal process, the round billet is pressed down by a plurality of first withdrawal straightening machines 510 and second withdrawal straightening machines 520 which are alternately arranged.

In addition, an end position may be provided on a side of the solidification end (i.e., a position having a solid fraction of 1) away from the start position, and in this case, the start position, the solidification end, and the end position may be arranged in order, and the first withdrawal and straightening unit 510 and the second withdrawal and straightening unit 520 may be alternately arranged between the start position and the end position.

Optionally, the position of the first bottom press roll 210 may be set between 0.6 and 1.0 of the central solid fraction of the round billet, and the first bottom press roll 210 can transfer the reduction amount to the inside of the round billet, so as to improve the problems of loosening and central shrinkage of the round billet, and improve the distribution uniformity of the solute of the round billet and the central density of the billet. The second press-down roller 220 is provided after the first press-down roller 210, and not only can transmit the amount of reduction to the inside of the round billet, but also can improve the final shape characteristics of the round billet.

Step 303, respectively determining a green compact force corresponding to each reduction when the reduction operation is performed at the reduction position according to each reduction in a plurality of preset reductions;

specifically, a plurality of reduction amounts are preset, and different green compact forces need to be applied to achieve different reduction amounts, so that at the solidification end, that is, at the position where the solid phase ratio is 1, it is determined how much green compact force is needed to achieve the preset reduction amounts, that is, the green compact force corresponding to each reduction amount is determined.

For example, an arc having a radius of 175mm is used as an initial roll profile for the first and second press-down rolls 210 and 220, and the thickness of the press-down rolls is set to

The rolling reductions of 20mm, 25mm, 30mm, 35mm and 40mm were set, and the press forces of the withdrawal straightening machine required for the completion of the rolling reductions were determined to be 118ton, 132ton, 146ton, 160ton and 176ton, respectively.

Further, the thickness of the press roller is arc radius

And on the premise of ensuring the surface quality of the press roll, the production material of the press roll is saved, and the production cost is reduced.

Step 304, selecting the maximum rolling reduction as a target rolling reduction R in a green compaction force less than or equal to a safe green compaction force;

specifically, the withdrawal and straightening unit is provided with a safe compaction force, which may damage the withdrawal and straightening unit if the compaction force is greater than the safe pressure. Therefore, it is determined whether the green compaction force corresponding to each reduction is less than or equal to the safe green compaction force, and one reduction corresponding to the green compaction force is selected as the target reduction among the green compaction forces that do not damage the withdrawal straightening machine. On the other hand, when the reduction amount is larger, the reduction efficiency is higher, and therefore, the maximum reduction amount can be selected as the target reduction amount.

For example, the reduction amounts are 20mm, 25mm, 30mm, 35mm and 40mm, respectively, and the green compaction forces for each reduction amount are 118ton, 132ton, 146ton, 160ton and 176ton, respectively. Since the safe compaction force of the withdrawal and straightening machine was 160ton, the target rolling reduction was selected among compaction forces of 160ton or less. In addition, since the maximum value of the rolling reduction corresponding to the compacting force is 35mm in the compacting force of 160ton or less, 35mm can be selected as the target rolling reduction.

Step 305, obtaining the diameter d of the round billet;

step 306, according to a = d-R,

calculating to obtain a first shape parameter, wherein the first shape parameter comprises a first minor semi-axis parameter a and a first major semi-axis parameter b;

specifically, the lower press roller is formed by rotating an elliptical arc and has an elliptical arc shape. The specific shape of the hold-down roller can be determined according to the major axis radius and the minor axis radius. Fig. 3 shows a perspective view of a first lower press roller 210, and fig. 4 shows a front view of the first lower press roller 210 having a thickness D and a diameter L, after determining a major axis radius and a minor axis radius, an ellipse can be determined according to the major and minor axis radii, and the arc of the ellipse can be rotated to obtain the first lower press roller 210. Therefore, the shape of the first press roller 210 can be changed by changing the sizes of the major-axis radius and the minor-axis radius, and thus the major-axis radius and the minor-axis radius are used as the shape parameters of the first press roller 210.

For example, when the diameter d of the round billet is 350mm and the maximum reduction R is 35mm, the first minor semi-axis parameter is as follows: a = d-R =350-35=315.0mm,

and the first major-semiaxis parameter is:

307, taking the diameters of the round billets as a second minor semi-axis parameter and a second major semi-axis parameter of a second shape parameter respectively;

for example, when the diameter d of the round billet is 350mm, the second minor axis parameter and the second major axis parameter of the second shape parameter are both 350mm.

Step 308, setting at least one third shape parameter, wherein a third short half shaft of the third shape parameter is larger than the first short half shaft parameter and smaller than the second short half shaft parameter, a third long half shaft parameter of the third shape parameter is smaller than the first long half shaft parameter and larger than the second long half shaft parameter, an arithmetic progression relationship is formed among the first short half shaft parameter, the at least one third short half shaft parameter and the second short half shaft parameter, an arithmetic progression relationship is formed among the first long half shaft parameter, the at least one third long half shaft parameter and the second long half shaft parameter, and the number of the third shape parameters is two;

specifically, one or more third shape parameters are set, wherein a third minor semi-axis parameter of the third shape parameters is between the first minor semi-axis parameter and the second minor semi-axis parameter, and a third major semi-axis parameter is between the first major semi-axis parameter and the second major semi-axis parameter. Thus, a plurality of different sets of shape parameters are provided for selection, and among the first shape parameter, the second shape parameter and the at least one third shape parameter, a suitable shape parameter can be selected to achieve a better depressing effect.

Optionally, an arithmetic progression relationship is provided among the first minor semi-axis parameter, the at least one third minor semi-axis parameter, and the second minor semi-axis parameter, and an arithmetic progression relationship is also provided among the first major semi-axis parameter, the at least one third major semi-axis parameter, and the second major semi-axis parameter. The third minor semi-axis parameter distribution set in this way is more uniform, and is beneficial to selecting the shape parameter with better pressing effect.

For example, where the first minor semi-axis parameter is 315.0mm, the first major semi-axis parameter is 388.9mm, and the second minor semi-axis parameter and the second major semi-axis parameter are both 350mm, if the third shape parameters are two, then the third minor semi-axis parameters of the two third shape parameters may be 326.7mm and 338.3mm, respectively, and the third major semi-axis parameters may be 375.9mm and 362.9mm, respectively. At this time, the first minor semi-axis parameter, the two third minor semi-axis parameters and the second minor semi-axis parameter have the following arithmetic progression relationship: 315.0mm,326.7mm,338.3mm and 350mm; and the first long semi-axis parameter, the two third long semi-axis parameters and the second long semi-axis parameter are in the following arithmetic progression relation: 388.9mm,375.9mm,362.9mm,350mm.

Step 309, determining each of the first shape parameter, the second shape parameter and the third shape parameter as a first shape parameter to be selected;

step 310, determining the surface strain value and the surface strain concentration of the round billet when the pressing operation is performed according to each first parameter to be selected;

311, taking a first parameter to be selected corresponding to the surface strain value as a second parameter to be selected under the condition that the surface strain value is smaller than the surface strain threshold and the surface strain concentration is smaller than the concentration threshold;

specifically, in the pressing process, if the surface strain value is too large or surface strain concentration occurs, the pressed round billet may have surface cracks and the like, which affect the quality of the product. Therefore, the surface strain value and the surface strain concentration corresponding to each first shape parameter to be selected can be determined, and the first shape parameter to be selected with the surface strain value and the surface strain concentration meeting the requirements is selected, so that cracks and the like on the surface of the round billet are avoided.

Further, strain cloud observation can be used to indicate the magnitude of the strain. The strain cloud chart can show the strain of different parts of a stressed object, namely a round billet, in a cloud pattern mode so as to clearly see the deformation condition.

Step 312, determining the central strain value of the round billet when the depressing operation is executed according to each second parameter to be selected;

313, comparing the central strain values, and taking the second to-be-selected parameter corresponding to the maximum central strain value as a first target shape parameter, wherein the first target shape parameter comprises a minor half axis parameter and a major half axis parameter;

specifically, in the pressing process, if the central strain value is larger, the central overstressing effect of the round billet is also large, and the pressing effect is better. Therefore, the central strain value corresponding to each second shape parameter to be selected can be determined, and the second shape parameter to be selected with the largest central strain value is selected as the first target shape parameter, so that the pressing effect is improved, and the density of the finished product is higher.

For example, one of the second shape parameters to be selected is: a =315mm, b =388.9mm, and its corresponding central strain value is 0.021; another second to-be-selected shape parameter is: a =326.7mm, b =375.9mm, which corresponds to a central strain value of 0.023, since 0.023>, 0.021, a =326.7mm, b =375.9mm was chosen as the first target parameter.

Step 314, determining a second target shape parameter of the second down-press roller 220, wherein the first target shape parameter is the same as the second target shape parameter;

This embodiment determines the stress and strain of the round billet after being sequentially pressed by the first and second press-down

rollers

210 and 220, and further determines whether the round billet has an excessive concentration of profit or an excessive concentration of strain due to an unreasonable shape of the press-down roller. And further comparing the central strain of the round billet in different roll shape schemes, and taking the roll shape scheme with small strain of the billet shell, no concentration and large central strain as the optimal roll shape scheme.

And step 315, controlling the first and second pinch rolls 210 and 220 to perform a pinch-off operation on the round billet according to the target pinch-off amount R.

In the above embodiment, after the target rolling reduction, the first target shape parameter, and the second target shape parameter are determined, the rolling operation is performed on the round billet by using the first and

second rolls

210 and 220 having the specific shapes according to the target rolling reduction to obtain a finished product that meets the requirements.

By applying the technical scheme of the embodiment, the initial position, the end position and the pressing position are determined by utilizing the solid phase ratio of each point on the central axis of the cylindrical round billet, the first pressing roller 210 and the second pressing roller 220 are alternately arranged between the initial position and the end position, and the target pressing amount is determined according to the safe pressing force which can be borne by the withdrawal and straightening machine according to the corresponding relation between different pressing amounts and the pressing force at the pressing positions. And further determining a plurality of different shape parameters according to the target rolling reduction and the diameter of the round billet, and selecting a proper shape parameter as a target shape parameter according to the strain degree when the different shape parameters are adopted. Finally, the round billet is subjected to a reduction operation using the first and

second reduction rollers

210 and 220 set at the target shape parameters according to the target reduction amount. According to the embodiment, the first press-down roller 210 and the second press-down roller 220 are alternately arranged, so that the shape of a finished product is more in accordance with the requirement of a round shape, the design of target press-down amount and target shape parameters is adopted, the press-down effect is improved, the compactness is higher, and cracks are less prone to being generated. The embodiment can control the stability of the surface quality of the continuous casting round billet in the process of pressing the round billet, surface crack expansion caused by pressing can be avoided, the deformation of the shell of the round billet can not be too large, and strain can not be excessively concentrated, so that the problem that new surface cracks are generated on the surface of the round billet due to a pressing process is avoided. Compared with the traditional pressing scheme, the pressing amount of the embodiment can be efficiently transmitted to the center of the round billet so as to improve the center segregation, the center shrinkage cavity and the center porosity of the round billet, increase the density and the homogeneity degree of the continuous casting round billet, effectively ensure the pressing efficiency of the round billet and greatly improve the internal quality of the continuous casting round billet.

Further, as a specific implementation of the method shown in fig. 1 and fig. 2, an embodiment of the present application provides a round billet pressing apparatus 500, as shown in fig. 5, the apparatus includes: a first withdrawal and straightening machine 510, a second withdrawal and straightening machine 520, a determination module 530, and a control module 540.

The first withdrawal and straightening machine 510 and the second withdrawal and straightening machine 520 are alternately arranged, each first withdrawal and straightening machine 510 comprises a pair of first press rolls which are oppositely arranged, each second withdrawal and straightening machine 520 comprises a pair of second press rolls which are oppositely arranged, the directions of the first press rolls and the second press rolls are mutually vertical, and the first target shape parameters of the first press rolls are the same as the second target shape parameters of the second press rolls;

a determining module 530, configured to determine target rolling reductions R corresponding to the first and second rolling rolls;

and the control module 540 is used for controlling the first rolling press roller and the second rolling press roller to perform rolling operation on the round billet according to the target rolling reduction R.

It should be noted that other corresponding descriptions of the functional modules related to the pressing device 500 for a round billet provided in the embodiment of the present application may refer to the corresponding descriptions in fig. 1 to fig. 5, and are not repeated herein.

Those skilled in the art will appreciate that the drawings are merely schematic representations of one preferred implementation scenario and that the elements or processes in the drawings are not necessarily required to practice the present application. Those skilled in the art can appreciate that the elements in the device in the implementation scenario may be distributed in the device in the implementation scenario according to the implementation scenario description, and may also be correspondingly changed in one or more devices different from the present implementation scenario. The units of the implementation scenario may be combined into one unit, or may be further split into a plurality of sub-units.

The above application serial number is merely for description and does not represent the superiority and inferiority of the implementation scenario. The above disclosure is only a few specific implementation scenarios of the present application, but the present application is not limited thereto, and any variations that can be considered by those skilled in the art are intended to fall within the scope of the present application.

Claims

1. A method of pressing a round billet, the method comprising:

alternately arranging first withdrawal and straightening machines and second withdrawal and straightening machines, wherein each first withdrawal and straightening machine comprises a pair of first press rolls arranged oppositely, each second withdrawal and straightening machine comprises a pair of second press rolls arranged oppositely, the directions of the first press rolls and the second press rolls are perpendicular to each other, and a first target shape parameter of the first press rolls is the same as a second target shape parameter of the second press rolls;

determining a target rolling reduction R corresponding to the first and second press-down rollers;

controlling the first press-lower roller and the second press-lower roller to perform pressing operation on the round billet according to the target pressing amount R;

before the controlling the first and second platen rollers to perform the pressing operation, the method further includes:

determining the first target shape parameter and the second target shape parameter, wherein the first target shape parameter comprises a minor semi-axis parameter and a major semi-axis parameter;

the first target shape parameter of the first press roll and the second target shape parameter of the second press roll specifically include:

obtaining the diameter d of the round billet;

calculating to obtain a first shape parameter according to the diameter d of the round billet and the target rolling reduction R, wherein the first shape parameter comprises a first minor half shaft parameter a and a first major half shaft parameter b;

setting at least one third shape parameter, wherein a third minor semi-axis parameter of the third shape parameter is greater than the first minor semi-axis parameter and less than the second minor semi-axis parameter, and a third major semi-axis parameter of the third shape parameter is less than the first major semi-axis parameter and greater than the second major semi-axis parameter;

selecting the first target shape parameter among the first shape parameter, the second shape parameter, and the at least one third shape parameter;

the selecting the first target shape parameter from the first shape parameter, the second shape parameter, and the at least one third shape parameter specifically includes:

determining a surface strain value and a surface strain concentration of the round billet when a depressing operation is performed with each of the first shape parameters to be selected;

taking a first to-be-selected shape parameter corresponding to the surface strain value as a second to-be-selected parameter under the condition that the surface strain value is smaller than a surface strain threshold and the surface strain concentration is smaller than a concentration threshold;

determining a central strain value of the round billet when the pressing operation is executed according to each second parameter to be selected;

2. The round billet pressing method according to claim 1, wherein the determining of the target pressing amounts R corresponding to the first and second press rolls specifically comprises:

the maximum reduction amount is selected as the target reduction amount R among green forces less than or equal to a safe green force.

3. A rolling method of a round billet according to claim 2, wherein said determining a green compaction force corresponding to each of said rolling reductions specifically comprises:

determining the position with the central solid phase ratio of 1 of the round billet as a pressing position;

4. The rolling method of the circular blank according to claim 1, wherein the step of calculating a first shape parameter according to the diameter d of the circular blank and the target rolling reduction R specifically comprises:

a＝d-R，

5. the round billet rolling method according to claim 1,

the first minor semi-axis parameter, the at least one third minor semi-axis parameter and the second minor semi-axis parameter are in an arithmetic progression relationship;

the first long half shaft parameter, at least one third long half shaft parameter and the second long half shaft parameter are in an arithmetic progression relationship;

wherein the number of the third shape parameters is two.

6. The round billet screw-down method according to claim 1, wherein the alternate arrangement of the first withdrawal straightening machine and the second withdrawal straightening machine specifically comprises:

and arranging one first withdrawal and straightening machine at the starting position, arranging one second withdrawal and straightening machine at the ending position, and alternately arranging other first withdrawal and straightening machines and other second withdrawal and straightening machines between the starting position and the ending position.

7. A round billet screwdown device, comprising:

the tension leveler comprises a first tension leveler and a second tension leveler, wherein the first tension leveler and the second tension leveler are alternately arranged, each first tension leveler comprises a pair of first press rolls which are oppositely arranged, each second tension leveler comprises a pair of second press rolls which are oppositely arranged, the directions of the first press rolls and the second press rolls are mutually vertical, and a first target shape parameter of each first press roll is the same as a second target shape parameter of each second press roll;

a determination module for determining a target rolling reduction R corresponding to the first and second rolling rolls;

the control module is used for controlling the first pressing roller and the second pressing roller to perform pressing operation on the round billet according to the target pressing amount R;

the determining module is further configured to determine the first target shape parameter and the second target shape parameter, wherein the first target shape parameter comprises a minor semi-axis parameter and a major semi-axis parameter; the method is specifically used for:

obtaining the diameter d of the round billet;

determining each of the first shape parameter, the second shape parameter and the third shape parameter as a first shape parameter to be selected;