CN109807269B - Design method of special-shaped building blank - Google Patents
Design method of special-shaped building blank Download PDFInfo
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- CN109807269B CN109807269B CN201910003085.1A CN201910003085A CN109807269B CN 109807269 B CN109807269 B CN 109807269B CN 201910003085 A CN201910003085 A CN 201910003085A CN 109807269 B CN109807269 B CN 109807269B
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Abstract
The invention relates to a design method of a special-shaped building blank, which designs the appearance of an hourglass-shaped blank by adopting finite element simulation and comprises the following steps: (1) starting from an initial state, calculating the pressing process of the blank, pressing the blank to a certain deformation, and then cutting off the bulging on the side surface of the blank due to pressing; (2) taking a plurality of reference points along the longitudinal center line of the section, carrying out reverse calculation, obtaining the corresponding positions of the reference points taken by the section in the initial state, and taking the initial positions of the reference points as the design basis of the blank shape; (3) modeling calculation is carried out on the blank shape designed according to the initial position of the reference point, and the bulging condition under the same rolling reduction is verified; (4) and correcting the design size of the blank shape according to the bulging condition calculated by primary modeling, so that the blank shape does not generate obvious bulging phenomenon when being deformed to the same rolling reduction. The method can effectively avoid the defects of instability, folding, cracking and the like possibly generated in the blank forging process.
Description
Technical Field
The invention relates to a manufacturing technology of metal materials, in particular to a design method of a special-shaped building blank.
Background
When large metal materials or composite metal materials are prepared, the existing method provides that a casting blank, a forging blank and a rolling blank are used as elements, a plurality of elements are packaged together after surface processing and cleaning, the interior of an interface is kept in a high vacuum state, and then a forging and welding process characterized by upsetting deformation, forging heat preservation and multidirectional forging is applied to finally prepare a large metal device. In these methods, the preform has a rectangular parallelepiped or cylindrical shape, and a weld is easily broken at a maximum bulging position (a central position of a side surface of the blank) of the rectangular parallelepiped or cylindrical blank during the construction. This is because the stress at the maximum bulging position (the central position of the side face of the billet) increases with the amount of deformation, the compressive stress decreases and finally becomes 0, and the stress at this position is converted into tensile stress if the deformation continues. The stress state of the surface is controlled by the degree of bulging. The more severe the bulge, the greater the surface tensile stress. When the surface tensile stress is greater than the strength of the weld, the weld will crack.
The Chinese patent application 201710837992.7 discloses a method for forming a special-shaped metal structure by making a preformed blank into an hourglass-shaped module, then heating the hourglass-shaped module, upsetting and deforming along the height direction and preserving heat between forgings, forge-welding the preformed blank into a blank, and finally processing the blank into parts or parts. The hourglass-shaped construction blank can enable deformation in the upsetting process to be concentrated at the interface position, avoids surface tensile stress, enables the blank to be uniformly subjected to larger compressive stress, and obviously improves the tensile stress state of the surface of the blank. Therefore, the special-shaped building blank has the characteristics of small interface position area, concentrated deformation, small required pressure and low requirement on equipment, and the interface combination of the building blank can be realized under small pressure. However, the shape of the special-shaped building blank is a special-shaped structure, which is greatly different from the shape of the traditional blank, and if the blank shape is improperly designed, the problems of local stress concentration, instability, folding and the like in the forging process can be caused, or cracks can be generated in the forging process, so that a design method of the special-shaped building blank shape with high accuracy and reliability must be researched.
Disclosure of Invention
The invention aims to provide a design method of a special-shaped construction blank aiming at the appearance characteristics of the special-shaped construction blank, thereby effectively avoiding bulging deformation of the blank in the upsetting process and preventing cracking.
The technical scheme of the invention is as follows: a design method for a special-shaped building blank designs the appearance of an hourglass-shaped blank by adopting a finite element simulation method, and comprises the following steps:
(1) starting from an initial state, calculating a pressing process of an initial blank, pressing the initial blank to a certain deformation amount, and then cutting off bulging generated by pressing the side surface of the deformed blank;
(2) taking a plurality of reference points along the longitudinal center line of the section, carrying out reverse calculation, obtaining the corresponding positions of the reference points taken by the section in the initial state, and taking the initial positions of the reference points as the design basis of the shape of the hourglass-shaped blank;
(3) modeling calculation is carried out on the shape of the hourglass-shaped blank designed according to the initial position of the reference point, and the bulging condition under the condition of the same rolling reduction as that in the step (1) is verified;
(4) and correcting the shape design size of the hourglass-shaped blank according to the bulging condition calculated by primary modeling, so that the hourglass-shaped blank does not generate obvious bulging phenomenon when the shape of the hourglass-shaped blank deforms to the same rolling reduction, and the final shape size of the hourglass-shaped blank is determined.
Further, the method for designing a special-shaped building block as described above, wherein the initial block in the step (1) is a square block or a cylindrical block or a hexagonal prism block or an octagonal prism block.
Further, the method for designing a special-shaped building blank as described above, wherein the deformation amount of the initial blank in the step (1) is 20% to 35%.
Further, in the method for designing a special-shaped building blank, when the hourglass-shaped blank is designed in the step (2), the side surfaces of the blank are symmetrically designed by taking the initial position of the reference point as a reference, so that the hourglass-shaped blank is formed.
Further, in the method for designing a special-shaped building blank, the step (4) of correcting the design size of the hourglass-shaped blank refers to performing smooth transition treatment on the middle position of the blank.
The invention has the following beneficial effects: the invention provides a shape design method for a special-shaped blank, the shape of the special-shaped blank is designed in a reverse calculation mode, and the method can effectively avoid the defects of instability, folding and the like possibly generated in the subsequent forging process. And comparing the actual forging result with the simulation value, and finding that the size error is very small, thereby verifying the accuracy of the model and the effectiveness of the design method.
Drawings
FIG. 1 is a flow chart of a method for designing the appearance of a special-shaped building blank according to the present invention;
FIG. 2-1 is a cross-sectional view of an hourglass shaped stainless steel blank in accordance with an embodiment of the present invention;
FIG. 2-2 is a perspective view of an hourglass-shaped stainless steel blank in accordance with an embodiment of the present invention;
FIG. 3-1 is a stress distribution diagram at a blank reduction of 30% according to an embodiment of the present invention;
3-2 are strain profiles at a blank reduction of 30% for an embodiment of the present invention;
FIG. 4-1 is a cross-sectional view of an optimized hourglass-shaped stainless steel blank profile in an embodiment of the present invention;
FIG. 4-2 is a perspective view of an optimized hourglass-shaped stainless steel blank profile in an embodiment of the present invention;
FIG. 5-1 is a stress distribution diagram of the optimized blank reduction rate of 30% according to the embodiment of the invention;
5-2 are strain profiles at 30% optimized blank reduction in an embodiment of the present invention;
FIG. 6 is a schematic diagram of a specially-shaped construction blank after 30% upsetting deformation in an embodiment of the invention.
Detailed Description
The invention is described in detail below with reference to the figures and examples.
The invention designs the appearance of the hourglass-shaped blank by adopting a finite element simulation method, and the design method comprises the steps as shown in the attached figure 1.
Step one, starting from an initial state, calculating a pressing process of a blank, pressing the blank to a certain deformation amount (20% -35%), and then cutting off a bulge on the side face of the blank due to pressing; the blank can be a square blank or a cylindrical blank in an initial state, or can also be a blank with other space symmetrical shapes, such as a hexagonal prism shape, an octagonal prism shape and the like;
secondly, taking a plurality of reference points along the longitudinal center line of a section, carrying out reverse calculation, obtaining the corresponding positions of the reference points taken by the section in the initial state, and taking the initial positions of the reference points as the design basis of the blank shape; taking the initial position of the reference point as a reference, symmetrically designing each side surface or the outer circumferential surface of the blank to form an hourglass-shaped blank;
step three, modeling calculation is carried out on the blank shape designed according to the initial position of the reference point, and the bulging condition when the rolling reduction is the same as that in the step one is verified; the stress-strain distribution of the round hourglass-shaped blank is different from that of a square blank in the initial shape in the deformation process, and slight bulging appears when the shape of the blank taking the tangent plane point as the reference is deformed to the same rolling reduction;
and step four, correcting the design size of the blank appearance according to the bulging condition calculated by primary modeling, and performing smooth transition treatment on the middle position of the blank to ensure that the blank appearance does not generate obvious bulging phenomenon when being deformed to the same rolling reduction, thereby determining the final appearance size of the blank.
The first embodiment is as follows: appearance design of 135t stainless steel construction blank
According to the method for designing the appearance of the special-shaped building blank, the appearance of the 135t stainless steel building blank is designed. The design content is that when the blank deforms 30%, no obvious bulging phenomenon is generated.
1. A 135t stainless steel blank of 2052mm in length by 2052mm in width by 4000mm in height was simulated with a 30% hold down and the bulge on one side was cut off.
2. The tangent plane is equally divided into 16 sections, and the position information of the reference point of the corresponding tangent plane is obtained, as shown in table 1, so that the distribution characteristic of the bulging shape is obtained. In table 1, column a is the distance of each reference point in the longitudinal direction relative to the middle position of the blank, and column B is the distance of each reference point corresponding to the position after bulging deformation relative to the initial side of the blank. According to the principle of equal volume, reverse calculation is carried out, after the process links of hoisting, forging and sealing welding are considered comprehensively, the inclination angle is determined to be 70 degrees, the length of the large end is 2548mm, the length of the small end is 1500mm, and the specific size is shown in figure 2-1.
TABLE 1
| Reference | A | B | |
| 1 | 1400 | 7 | |
| 2 | 1225 | 18 | |
| 3 | 1050 | 72 | |
| 4 | 875 | 140 | |
| 5 | 700 | 208 | |
| 6 | 525 | 276 | |
| 7 | 350 | 343 | |
| 8 | 175 | 411 | |
| 9 | 0 | 479 | |
| 10 | 175 | 411 | |
| 11 | 350 | 343 | |
| 12 | 525 | 276 | |
| 13 | 700 | 208 | |
| 14 | 875 | 140 | |
| 15 | 1050 | 72 | |
| 16 | 1225 | 18 | |
| 17 | 1400 | 7 |
3. The new blank was re-simulated to calculate the depression of 30%, and the outside of the middle portion was found to have a phenomenon of strain concentration, as shown in FIGS. 3-1 and 3-2. Therefore, the outer dimensions need to be re-optimized.
4. The middle of the blank is smoothly transited, and the optimized external dimension is shown as figure 4-1. After the blank is pressed down by 30% through simulation calculation, the strain distribution of all parts of the blank is uniform, and the strain of the middle position is maximum and is uniform. Thus determining the final dimensions.
Fig. 3-1 and 3-2 are stress and strain profiles, respectively, for a billet cross-section at a 135t hourglass parison reduction of 30%. As can be seen from the figure, when the pressing force reaches 30%, the blank has a substantially square shape, the stress distribution in the compression direction is uniform, the blank is in a compressive stress state, and the compressive stress is greater in the middle portion than in other portions. It can be seen from the strain distribution diagram that the strain distribution of each part of the blank is relatively uniform, and the strain of the middle position is maximum and is uniformly distributed. However, the strain concentration phenomenon exists outside the middle part, and is mainly caused by the fact that the middle part of the initial blank shape has no smooth transition.
The optimized scheme mainly carries out smooth transition treatment on the middle position of the blank, the section shape of the optimized blank is shown as figure 4-1, and figure 4-2 shows the shape of the optimized hourglass-shaped blank.
Fig. 5-1 and 5-2 are stress and strain distributions, respectively, for a section of a blank at a reduction of 30% after optimization of the shape of a 135t hourglass parison. As can be seen from the figure, when the pressing force is 30%, the outer shape of the blank is square, and it can be seen from the strain distribution diagram that the strain distribution of each part of the blank is relatively uniform, and the strain is maximum and uniformly distributed at the middle position. The stress distribution in the compression direction is uniform and is in a compressive stress state, and the compressive stress is larger in the middle part compared with other parts, so that the stress concentration phenomenon is avoided. The maximum compressive stress value of the surface part can effectively prevent the weld joint from cracking and enhance the welding effect of the metal interface.
Example two: verification of appearance design of Q345 special-shaped blank
The Q345 special-shaped blank designed by the method is upset and deformed by 30 percent along the height direction, and the outline dimension schematic diagram is shown in figure 6. The comparison results of the simulation calculation and the actual measurement value of each position size are shown in table 2.
TABLE 2 comparison of simulation and measured values
| Location numbering | Measured size | |
| 1 | 1210 | 1092 |
| 2 | 1240 | 1180 |
| 3 | 1124 | 1144 |
| 4 | 1184 | 1092 |
| 5 | 957 | 955 |
The actual forging result is compared with the simulation value, and the small size error can be found, so that the accuracy of the model and the effectiveness of the design method are verified.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is intended to include such modifications and variations.
Claims (5)
1. A design method for a special-shaped building blank designs the appearance of an hourglass-shaped blank by adopting a finite element simulation method, and comprises the following steps:
(1) starting from an initial state, calculating a pressing process of an initial blank, pressing the initial blank to a certain deformation amount, and then cutting off bulging generated by pressing the side surface of the deformed blank;
(2) taking a plurality of reference points along the longitudinal center line of a section, carrying out reverse calculation, obtaining the corresponding positions of the reference points taken by the section in the initial state, and taking the initial positions of the reference points as the design basis of the shape of the hourglass-shaped blank;
(3) modeling calculation is carried out on the shape of the hourglass-shaped blank designed according to the initial position of the reference point, and the bulging condition under the condition of the same rolling reduction as that in the step (1) is verified;
(4) and correcting the shape design size of the hourglass-shaped blank according to the bulging condition calculated by primary modeling, so that the hourglass-shaped blank does not generate obvious bulging phenomenon when the shape of the hourglass-shaped blank deforms to the same rolling reduction, and the final shape size of the hourglass-shaped blank is determined.
2. A method of designing a profiled building block as claimed in claim 1, wherein: in the initial state of the initial blank in the step (1), the blank is a square blank or a cylindrical blank or a hexagonal prism blank or an octagonal prism blank.
3. A method of designing a profiled building block as claimed in claim 1, wherein: the deformation of the initial blank in the step (1) is 20-35%.
4. A method of designing a profiled building block as claimed in claim 2, wherein: and (3) when the appearance of the hourglass-shaped blank is designed in the step (2), symmetrically designing the side surface of the blank by taking the initial position of the reference point as a reference to form the hourglass-shaped blank.
5. A method of designing a profiled building block as claimed in claim 1, wherein: the step (4) of correcting the shape design size of the hourglass-shaped blank refers to the step of performing smooth transition treatment on the middle position of the blank.
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