CN109759531B - X-section drawing method based on center compaction - Google Patents

Abstract

The invention discloses an X-section elongation method based on center compaction. T-shaped narrow anvils are used to extrude concave shapes on the upper, lower and left and right sides respectively, so that the cross-sectional contour of the prefabricated blank is X-shaped, which is designed according to the requirements of the method. A T-shaped narrow anvil is produced. The front end boss of the T-shaped narrow anvil is a concave shape required for elongation. The T-shaped narrow anvil can make the initial blank still maintain a suitable size of concave under a large reduction. shape. At this time, the metal core is easily forged through, which can inhibit the lateral cracking of the core; the flat end face of the front-end boss of the T-shaped narrow anvil presses down the protruding metal on both sides of the opposite side of the prefabricated blank respectively, and the protruding metal from the corners is raised from the four corners. Pressing into the main body of the prefabricated billet suppresses the diagonal shear strain of the core and eliminates diagonal looseness; at the same time, the concave shapes on the left and right sides of the prefabricated billet will generate a compressive stress component directed to the core, which can reduce or even eliminate the transverse tensile stress of the core. Finally, the high-quality completion of the initial blank drawing work is realized.

Description

X-section Elongation Method Based on Center Compaction

technical field

The invention relates to the technical field of metal forging, in particular to an X-section elongation method based on center compaction.

Background technique

During the elongation of rectangular section metal forgings, defects such as core cracking and diagonal looseness often occur, which are caused by the transverse tensile stress at the core of the forging cross-section and the shear strain at the diagonal. Defects directly affect the quality of forgings.

In order to solve the above problems, according to the mechanical theory and experimental research results, the current commonly used methods can be summarized into the following aspects: First, when the flat anvil is used to draw the length, by reasonably adjusting the anvil width ratio and the material width ratio, the core of the forging can be fully It is possible to obtain sufficient deformation under the hydrostatic pressure to achieve the purpose of compacting the core. However, limited by the reasonable range of the anvil width ratio and the material width ratio, the amount of pressing down each time should not be too large, which will affect the work efficiency; Change the shape of the anvil, such as V-shaped anvil, trapezoidal anvil, etc., to reduce or even eliminate the transverse tensile stress of the core to achieve the purpose of compacting the core. However, the load required by each method is doubled, and it is difficult to control the transverse tension of the forging. The uniformity of the cross-section deformation affects the quality of the forging forming; the third is to use the rapid water cooling method to change the internal temperature gradient of the blank before forging. The surface metal is rapidly cooled to form a hard shell. The narrow anvil is used to lengthen, so that the core can obtain a large deformation under a small reduction, so as to achieve the purpose of compacting the core. However, due to factors such as heat conduction, the temperature inside and outside the forging is very high during work. It tends to be balanced quickly, and the constraining effect of the outer hard shell layer is weakened. Therefore, the working time is very short, the work is tense, and the quality of the heart is not easy to guarantee.

SUMMARY OF THE INVENTION

In view of the above problems, the present invention provides an X-section elongation method based on center compaction, the purpose is to improve the shortcomings of the previous methods, and the elongation method for improving the quality of the rectangular section blank core, which is especially suitable for large-scale long shafts Rectangular-like section blank drawing process.

The technical solution of the present invention is to provide a method for elongating an X section, using a T-shaped narrow anvil to extrude concave shapes on the upper, lower, left and right sides, respectively, to obtain the prefabricated blank with an X-shaped cross-sectional profile, and using the The T-shaped narrow anvil re-presses the prefabricated blank with an X-shaped cross-sectional profile, so as to change the internal mechanical state of the blank when the flat anvil draws the rectangular-section blank. The T-shaped narrow anvil can make the initial blank under large pressure The desired concave shape and size is maintained under measurement. Based on the theory of metal plasticity mechanics, when the flat end of the front end boss of the T-shaped narrow anvil is used to press the X-shaped prefabricated blank, under the influence of the protruding metal at the upper and lower sides of the prefabricated blank, no production will occur. The cross section is approximately triangular in the difficult-to-deform area, thereby disrupting the shear strain area inside the blank, so that when the X-shaped prefabricated blank exceeds the range of the material width ratio, the shear stress in the diagonal direction of the core will not appear, and the deformation of the prefabricated blank will be suppressed. The generation of corner cracks, and in the process of pressing down, the X-shaped prefabricated blank will have a lateral compressive stress component under the influence of the concave shape on both sides, so that the core part can be ensured even under a large material width ratio. Transverse tensile stress occurs.

The specific implementation steps in the drawing process are as follows:

(1) According to the final size required by the finished product blank, select a suitable anvil type. The selection of the T-shaped narrow anvil specification is based on the principle that the length L of the flat end face of the front end boss of the T-shaped narrow anvil should be greater than the specified length L. The final size of the finished blank is preferably in the range of 15% to 20% larger than the final size of the finished blank. The height H of the front end boss of the T-shaped narrow anvil can be appropriately selected according to the requirements of the drawing pass, and the preferred range is 10% to 20% of the final size of the finished blank, the slope α of the front end boss of the T-shaped narrow anvil is preferably in the range of 20° to 40°, and the anvil width ratio of the T-shaped narrow anvil is preferably in the range of 0.5 to 0.9. between;

(2) Use the T-shaped narrow anvil part to press the upper and lower surfaces of the initial blank with a suitable size of concave surface and then continue to press down, the purpose is to completely forge the core of the blank, and the pressing amount is appropriate, but it needs Make the height of the pressed initial blank greater than the width of the flat end face of the front end boss of the T-shaped narrow anvil, so that the other two surfaces are subjected to embossing treatment after the initial blank is turned 90° clockwise along its central X axis;

(3) Then turn the initial blank 90° clockwise along its central X axis, and press down the other two surfaces with appropriate concave surfaces, so that the height of the prefabricated blank is smaller than the front end boss of the T-shaped narrow anvil The purpose is to make the prefabricated blank turn 90° clockwise along its central X axis, and the entire upper surface of the prefabricated blank can be pressed by using the front-end boss part of the T-shaped narrow anvil, so that there is no need to change the anvil; finally Make the cross-sectional profile an X-shaped preform. In the process of (2) and (3), due to the large deformation of the metal under the narrow anvil of the T-shaped shape, the metal in the core is easily forged through, so it will not cause transverse cracks in the core, so as to achieve the compaction of the core. the role of;

(4) Turn the X-shaped prefabricated blank 90° clockwise along its central X axis again, and use the flat end face of the front end boss of the T-shaped narrow anvil to press down the protruding metal at the upper and lower sides of the X-shaped prefabricated blank, Metal press this area into the inside of the X-shaped preform body until flattened. During this process, the raised metal at the corners is pressed into the main body of the X-shaped prefabricated blank from the four corners, so as to suppress the generation of shear strain in the diagonal direction of the core, thereby eliminating the diagonal porosity defect. During the entire pressing process, the concave surfaces on the left and right sides form a pressure component directed towards the heart, which can keep the heart laterally compressed; according to this method, for the third time, the prefabricated blanks that have been flattened on the upper and lower sides are clockwise along its central X axis. Flip 90° and press the other two sides until the specified size is completed;

In the above step (4), if the height of the prefabricated blank does not meet the size requirements of the finished blank after the upper surface is flattened, continue to press down so that the cross-sectional profile continues to be X-shaped; then the X-shaped prefabricated blank is moved along its The central X-axis is turned 90° clockwise, and the flat end surface of the front end boss of the T-shaped narrow anvil is used to press down the metal raised at the corners of the other two surfaces again. The size requirements of the finished blanks can be flattened. If the height of the prefabricated blanks after flattening the upper surface still does not meet the size requirements of the finished blanks, repeat the above operation until the height of the prefabricated blanks after the upper surface is flattened reaches the stated height. The size of the finished blank is required, and then the prefabricated blank that has been flattened on the upper and lower sides is turned 90° clockwise along its central X axis, and the other two surfaces are flattened to finally obtain the finished blank that meets the size requirements.

Preferably, the front end boss of the T-shaped narrow anvil is in a concave shape required for drawing.

Preferably, when the T-shaped narrow anvil presses the initial blank of rectangular section, because the width of the front end boss of the T-shaped narrow anvil is narrow, the deformation of the metal below is large, and the metal at the core is easily forged through. Therefore, It will not cause transverse cracks in the core, and continue to press down after the desired concave shape is extruded, so that the core can obtain greater deformation. After the end face width is determined, the entire upper surface of the prefabricated blank can be pressed by using the flat end face of the front end boss of the T-shaped narrow anvil without changing the anvil.

Preferably, the flat end face of the front end boss of the T-shaped narrow anvil presses the upper and lower opposite corner protruding metals of the X-shaped prefabricated blank, and no diagonal shear strain area is formed inside the X-shaped prefabricated blank, and Due to the compressive stress component directed towards the core produced by the concave shapes on the left and right sides of the X-shaped preform, the core is always in a state of compressive stress, thereby suppressing the occurrence of defects such as porosity in the diagonal direction and transverse cracks.

Preferably, the selection of the T-shaped narrow anvil specification follows the principle that the length L of the flat end face of the front end boss of the T-shaped narrow anvil should be greater than the final size of the finished blank, and the preferred range is greater than the final size of the finished blank The height H of the front end boss of the T-shaped narrow anvil can be appropriately selected according to the requirements of the drawing length, and the preferred range is 10% to 20% of the final size of the finished blank. The preferred range of the slope α of the front end boss is between 20° and 40°, and the preferred range of the anvil width ratio of the T-shaped narrow anvil is between 0.5 and 0.9.

Preferably, the principle followed for the selection of the range of the single pressing amount during drawing is that after the first pressing amount is the desired concave shape, the second pressing is about 5% to 8% of the initial blank height, i.e. Yes, the second pressing amount is to press down again after extruding the desired concave shape, and the pressing amount is that the height of the prefabricated blank after pressing is less than the length L of the flat end face of the front end boss of the T-shaped narrow anvil, so that the prefabricated blank after pressing is pressed. The height is about 85% to 95% of L. The cross-sectional area of the blank is reduced due to the axial elongation of the blank, so the amount of reduction in the next few times is gradually reduced compared with the amount of the second reduction. According to the final size and It depends on the number of flips, which is appropriate.

Preferably, starting from the shape of the blank, to improve the mechanical state of the core, and design the T-shaped narrow anvil, so that the desired shape of the blank can be obtained during the elongation process, and there is no need to adjust the shape before elongation. The blanks undergo any preprocessing.

Compared with the traditional drawing process, the present invention has those following advantages:

An X-section elongation method does not need to form a reasonable temperature gradient in advance. At the same time, the T-shaped narrow anvil used in the work not only does not increase the required load, but also slightly reduces compared with the ordinary flat anvil. When the T-shaped narrow anvil presses the initial blank into the X-shaped prefabricated blank, it will break the limitation of the material width ratio when the flat anvil draws the rectangular section blank in the past, and improves the stress state of the forging core by changing the shape of the blank, making it At a larger material-width ratio, transverse tensile stress will not be formed, so that the single reduction can be appropriately increased, and the drawing efficiency and forming quality can be improved.

Description of drawings

Fig. 1 is the T-shaped narrow anvil used by the X-section drawing method based on center compaction of the present invention;

Fig. 2a-Fig. 2f is the schematic flow chart of the X-section elongation method based on center compaction of the present invention;

3a-3b are the comparison of the internal shear strain field of the X-section elongation method based on center compaction and the flat anvil elongation process of the present invention; and

4a-4b are the comparison of the internal transverse stress field of the X-section elongation method based on center compaction and the flat anvil elongation process of the present invention.

Main reference signs:

Upper anvil 1; initial blank 21; prefabricated blank 22; corner raised metal 23; concave shape 24; finished blank 25;

Detailed ways

In order to detail the technical content, achieved objects and effects of the present invention, the following will be described in detail with reference to the accompanying drawings.

In a method for elongating an X-section of the present invention, a T-shaped narrow anvil is used to extrude a concave shape on the upper, lower, left and right faces, respectively, to obtain a prefabricated blank with an X-shaped cross-sectional profile, and a T-shaped narrow anvil is used to extrude the cross-sectional profile. The X-shaped prefabricated billet is pressed again, thereby changing the mechanical state inside the billet when the flat anvil draws the rectangular section billet, and the T-shaped narrow anvil can keep the initial billet in the desired concave shape and size. A T-shaped narrow anvil is designed according to the needs of the drawing method. As shown in Figure 1, L is the length of the front end boss of the T-shaped narrow anvil, H is the height of the front end boss of the T-shaped narrow anvil, and α is the T-shaped narrow anvil. Front end boss slope. The front end boss of the T-shaped narrow anvil is a concave shape required for drawing, and the T-shaped narrow anvil can keep the blank in a suitable size of the concave shape under a large reduction.

The main implementation steps are as follows:

Step 1: According to the final size required by the finished blank 25, select the appropriate anvil type. The overall shape of the anvil type is a T-shaped narrow anvil. The principle of the anvil type specification is the length of the flat end face of the front end boss of the T-shaped narrow anvil. L should be larger than the final size of the finished blank 25, and the preferred range is 15% to 20% larger than the final size of the finished blank. The height H of the front end boss of the T-shaped narrow anvil can be selected appropriately according to the requirements of the drawing passes. The preferred range is the finished product. 10% to 20% of the final size of the blank, the preferred range of the front end boss slope α of the T-shaped narrow anvil is between 20° and 40°, and the preferred range of the anvil width ratio of the T-shaped narrow anvil is between 0.5 and 0.9;

Step 2: heating the initial blank 21 to the initial forging temperature of 1100°C;

Step 3: Place the initial blank 21 on the position of the lower anvil 3, as shown in Figure 2a;

Step 4: Use the T-shaped narrow anvil to press the initial blank 21 with the rectangular section, and press down the concave shape 24 with the same shape as the boss, as shown in Figure 2b;

Step 5: Turn the initial blank 21 with the concave shape 24 on the upper and lower sides clockwise by 90° once along its central X axis, as shown in Figure 2c, and press the other two sides, as shown in Figure 2d, using a T-shaped narrow anvil Press down again the other two surfaces are also concave 24, so that the cross section of the initial blank 21 is X-shaped, which becomes the prefabricated blank 22 required for the subsequent steps;

Step 6: When the cross section of the prefabricated blank 22 is X-shaped, continue to press down, so that the height of the prefabricated blank 22 is slightly smaller than the width of the flat end face of the front end boss of the T-shaped narrow anvil, the purpose is to make the prefabricated blank 22 clockwise along its central X axis After the second turning of 90°, the entire upper surface of the prefabricated blank 22 can be pressed by using the flat end face of the front end boss of the T-shaped narrow anvil, so that there is no need to change the anvil;

Step 7: Turn the prefabricated blank 22 clockwise by 90° twice along its central X-axis, as shown in Figure 2e, use the flat end face of the front end boss of the T-shaped narrow anvil to press the raised metal 23 at the corners on the upper and lower sides until the To flatten;

Step 8: If the size is close to the final required size after the upper surface is flattened, proceed to step 11. If the height of the prefabricated blank 22 does not reach the final required size, continue to press down so that the cross-sectional profile of the prefabricated blank 22 continues to be X-shaped ;

Step 9: Then turn the prefabricated blank 22 clockwise by 90° again along its central X axis, and use the flat end face of the front end boss of the T-shaped narrow anvil to press down the corner protruding metal 23 on the other two faces again until it is flattened;

Step 10: If the height of the prefabricated blank 22 does not reach the final required size, repeat step 8, continue to press down, and after the upper surface is flattened, the height of the prefabricated blank 22 has reached the final size requirement, and then it can be flattened;

Step 11: Then turn the prefabricated blank 22 90° clockwise along its central X-axis, as shown in Figure 2f, use the flat end face of the front end boss of the T-shaped narrow anvil to press the corner raised metal 23 on both sides of the other two faces, The prefabricated blank 22 is elongated to the final required size, and finally a finished blank 25 that meets the final required size is obtained.

Below in conjunction with embodiment, a kind of X-section elongation method of the present invention is further described:

Example 1:

The initial blank 21 is a cube with a cross-section of 500mm*500mm, and the finished blank 25 is elongated to a cube with a cross-section of 300mm*300mm.

According to the final size required by the finished blank 25, the specifications of the T-shaped narrow anvil and anvil are as follows: the length of the front end boss of the T-shaped narrow anvil is L=36mm, the front end boss height of the T-shaped narrow anvil is H=4mm, and the The slope of the front end boss is α=30°, and the anvil width ratio of the T-shaped narrow anvil is 0.8.

The steps of pulling out are as follows:

(1) heating the initial blank 21 to the initial forging temperature of 1100°C;

(2) The initial blank 21 is placed symmetrically between the upper anvil 1 and the lower anvil 3;

(3) the lower anvil 3 remains fixed, and the upper anvil 1 presses down the initial blank 21, and the first pressing amount is 200 mm;

(4) Turn the initial blank 21 clockwise by 90° along its center X axis, the lower anvil 3 remains fixed, the upper anvil 1 continues to press down on the initial blank 21, and the second pressing amount is 320 mm, at this time obtain A prefabricated blank 22 with an X-shaped cross section;

(5) the prefabricated blank 22 is turned 90° clockwise along its center X axis, the lower anvil 3 remains fixed, and the upper anvil 1 continues to press down on the prefabricated blank 22, and the amount of pressing down for the third time is 250mm;

(6) the prefabricated blank 22 is turned 90° clockwise along its center X axis, the lower anvil 3 is kept fixed, and the upper anvil 1 continues to press down the prefabricated blank 22, and the amount of pressing down for the fourth time is 250mm;

(7) Turn the prefabricated blank 22 clockwise by 90° along its central X axis, the lower anvil 3 remains fixed, the upper anvil 1 continues to press down on the prefabricated blank 22, and the concave shape 24 can be flattened. The fifth time The amount of pressing down is about 100mm.

Embodiment 2:

The initial blank 21 is a cube with a cross-section of 500mm*500mm, and the finished blank 25 is elongated to a cube with a cross-section of 250mm*250mm.

According to the final size required by the finished blank 25, the specifications of the T-shaped narrow anvil and anvil are as follows: the length of the front end boss of the T-shaped narrow anvil is L=30mm, the front end boss height of the T-shaped narrow anvil is H=3mm, and the The slope of the front end boss is α=30°, and the anvil width ratio of the T-shaped narrow anvil is 0.8.

The steps of pulling out are as follows:

(1) heating the initial blank 21 to 1100°C;

(2) The initial blank 21 is placed symmetrically between the upper anvil 1 and the lower anvil 3;

(3) the lower anvil 3 is kept fixed, and the upper anvil 1 is pressed down, and the amount of pressing down for the first time is 220mm;

(4) Turn the initial blank 21 clockwise by 90° along its central X axis, the lower anvil 3 remains fixed, the upper anvil 1 continues to press down on the initial blank 21, and the second pressing amount is 340mm, at this time obtain A prefabricated blank 22 with an X-shaped cross section;

(5) the prefabricated blank 22 is turned 90° clockwise along its center X axis, the lower anvil 3 remains fixed, and the upper anvil 1 continues to press down on the prefabricated blank 22, and the amount of pressing down for the third time is 250mm;

(6) the prefabricated blank 22 is turned 90° clockwise along its center X axis, the lower anvil 3 remains fixed, and the upper anvil 1 continues to press down on the prefabricated blank 22, and the amount of pressing down for the fourth time is 170mm;

(7) the prefabricated blank 22 is turned 90° clockwise along its center X axis, the lower anvil 3 remains fixed, and the upper anvil 1 continues to press down the prefabricated blank 22, and the amount of the fifth pressing is 150mm;

(8) Turn the prefabricated blank 22 90° clockwise along its central X axis, the lower anvil 3 remains fixed, the upper anvil 1 continues to press down on the prefabricated blank 22, and the concave shape 24 can be flattened. The sixth time The down pressure is about 60mm.

In order to better highlight the advantages of the X-section elongation method, the internal shear strain field in the X-section elongation method and the flat anvil elongation method was compared and analyzed.

Figure 3a is the result of the shear strain field obtained by the method of elongating the X section, and Figure 3b is the result of the shear strain field obtained by the flat anvil pulling the rectangular section blank. In the case of a rectangular section blank, if the rectangular section blank exceeds the range of the material width ratio, due to the influence of the friction between the anvil surface and the blank surface, a difficult-to-deform area with a cross-sectional approximately triangular cross-section will be formed. The shear strain area in the shape of the angle line will not disappear until the rectangular section blank enters a reasonable range of material width ratio, so that the shear stress in the diagonal direction of the core will appear for a period of time during the drawing process. After the center X axis is turned 90°, if the rectangular section blank still exceeds the range of the material-to-width ratio, the shear stress in the diagonal direction of the core will continue to appear. Line cracks.

In the X-section elongation method, due to the difference between the X-shaped section and the rectangular section, under the influence of the protruding metal at the corners of both ends, a difficult-to-deform area with a cross-section similar to a triangle will not be generated, thereby disrupting the interior of the blank. In this way, when the X-shaped section blank exceeds the range of the material width ratio, the shear stress in the diagonal direction of the core will not appear, and the generation of diagonal cracks will be suppressed.

In order to better highlight the advantages of the X-section elongation method, a comparative analysis of the internal transverse stress field between the X-section elongation method and the flat anvil elongation method is carried out.

Figure 4a is the result of the transverse stress field obtained by the X-section drawing method, and Figure 4b is the result of the transverse stress field obtained by the flat anvil drawing process. If the rectangular section billet exceeds the range of the material width ratio, transverse tensile stress will appear in the core, and during the solidification of the ingot, the core is more prone to defects such as pores, inclusions, and coarse grains, so that the core of the billet is very small. Cracks will occur under the action of transverse tensile stress.

The X-section elongation method is carried out under the same material-to-width ratio. Under the influence of the "concave" shape on both sides of the X-section blank, a transverse compressive stress component will be generated, so that it can be guaranteed even under a large material-to-width ratio. The core does not generate transverse tensile stress.

The above-mentioned embodiments are only to describe the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, those of ordinary skill in the art can make various modifications to the technical solutions of the present invention. Such deformations and improvements shall fall within the protection scope determined by the claims of the present invention.

Claims (5)

1. A central compaction-based X-section drawing method is characterized in that a T-shaped narrow anvil is used for respectively pressing concave shapes on the upper surface, the lower surface, the left surface and the right surface of the blank to obtain a prefabricated blank with an X-shaped cross section profile, and then the T-shaped narrow anvil is used for carrying out secondary pressing on the prefabricated blank with the X-shaped cross section profile, so that the internal mechanical state of the blank is changed when the blank with the rectangular section is drawn by a flat anvil, the T-shaped narrow anvil can enable an initial blank to still keep the required concave shape and size under large pressing amount, and the specific implementation steps are as follows:

(1) pressing the initial blank with the rectangular cross section in the up-down direction by using the T-shaped narrow anvil to press a required concave shape, then clockwise turning the initial blank by 90 degrees along the central X axis of the initial blank, then pressing down again by using the T-shaped narrow anvil to press the required concave shape, and finally obtaining a prefabricated blank with the X-shaped cross section profile; when the T-shaped narrow anvil presses an initial blank with a rectangular cross section, the width of a boss at the front end of the T-shaped narrow anvil is narrow, the contact surface of the initial blank is larger than that of the T-shaped narrow anvil, so that the center of the initial blank cannot generate transverse cracks, and meanwhile, after the height of the prefabricated blank is smaller than the width of the flat end surface of the boss at the front end of the T-shaped narrow anvil, the whole upper surface of the prefabricated blank can be pressed by using the flat end surface of the boss at the front end of the T-shaped narrow anvil;

(2) pressing the convex metal at the corner part of the X-shaped prefabricated blank, which is opposite to the upper part and the lower part, downwards by using the flat end surface of the boss at the front end of the T-shaped narrow anvil, pressing the metal into the X-shaped prefabricated blank, and then continuously pressing downwards by a preset pressing amount according to the required size of the finished blank; then, the prefabricated blank is turned over 90 degrees clockwise along the central X axis of the prefabricated blank, the flat end face of the boss at the front end of the T-shaped narrow anvil is utilized to press down the corner protruding metals on the two remaining faces again, and after the metals are pressed into the prefabricated blank, the pressing down is continued according to the final size required by the finished blank; finally obtaining the finished blank meeting the size requirement.

2. The center-compaction-based X-section drawing method according to claim 1, wherein the front end boss of the T-shaped narrow anvil is concave in shape required for drawing.

3. The center-compaction-based X-section elongation method as claimed in claim 1, wherein the flat end surfaces of the T-shaped narrow anvil front end bosses press down the upper and lower opposite corner convex metals of the X-shaped precast blank, so that no diagonal shear strain zone is formed inside the X-shaped precast blank, and the core part is always in a compressive stress state due to the compressive stress component directed to the core part generated by the left and right concave shapes of the X-shaped precast blank, thereby inhibiting the generation of diagonal looseness and transverse cracks.

4. The center-compaction based X-section elongation method according to claim 3, wherein the T-shaped narrow anvil specification is selected such that the flat end face length L of the T-shaped narrow anvil nose boss is greater than 15% to 20% of the final dimension of the finished blank, the T-shaped narrow anvil nose boss height H ranges from 10% to 20% of the final dimension of the finished blank, the T-shaped narrow anvil nose boss slope α ranges from 20 ° to 40 °, and the T-shaped narrow anvil width ratio ranges from 0.5 ° to 0.9.

5. The method for drawing an X-section based on center compaction according to claim 4, wherein the range of the single pressing amount during drawing is selected such that the pressing amount is 5% -8% of the initial blank height after the first pressing amount is the concave shape required for extrusion, and the pressing amount is 5% -95% of the L after the second pressing amount is the concave shape required for extrusion, and the pressing amount is that the height of the prefabricated blank after pressing is less than the length L of the flat end face of the boss at the front end of the T-shaped narrow anvil, so that the height of the prefabricated blank after pressing is 85% -95% of the L.

Images