CN115283597A

CN115283597A - Forging method and forming die for super-large-diameter thin-wall arc-shaped forging with boss

Info

Publication number: CN115283597A
Application number: CN202210950235.1A
Authority: CN
Inventors: 陶志勇; 梁剑雄; 李兆银; 王长军; 黄健; 刘振宝; 杨观强; 杨志勇; 艾海昆
Original assignee: Shanghai Electric Shmp Casting & Forging Co ltd; Central Iron and Steel Research Institute
Current assignee: Shanghai Electric Shmp Casting & Forging Co ltd; Central Iron and Steel Research Institute
Priority date: 2022-08-09
Filing date: 2022-08-09
Publication date: 2022-11-04

Abstract

The invention relates to a forging method and a forming die for a thin-wall arc forging with a boss and an oversized diameter, wherein the method comprises the following steps: (1) blank preparation; (2) a step of changing the square billet into a triangular billet; (3) forming the trapezoidal blank; and (4) a final forming stage. Its advantages are: the invention solves the problem of forging and forming the ultra-large diameter thin-wall arc forging with the boss and designs the corresponding forming die. The required thin-wall arc forging piece is finally formed by manufacturing a square section blank, chamfering, manufacturing a triangular section blank, pressing a trapezoidal section blank, pressing two isosceles corners of a trapezoid in the final forming stage, and realizing the bending of a long strip shape through the difference of the forging rheology of the upper side and the lower side of the trapezoidal section blank. According to the method, a series of simple free forging operations are performed, so that the forge piece with continuous integral forging texture can be obtained on the basis of ensuring the shape and size of the forge piece, and the product quality is obviously improved.

Description

Forging method and forming die for ultra-large-diameter thin-wall arc-shaped forging with boss

Technical Field

The invention relates to the technical field of forging, in particular to a forging method and a forming die for an oversized-diameter thin-wall arc-shaped forging piece with a boss.

Background

The arc forging belongs to an extra-large equipment forging, the diameter of the arc forging is extremely large, the outer diameter reaches 11000mm, the width is nearly 1500mm, the wall thickness is only 300mm, the arc length reaches 15000mm, the arc forging is provided with a full-section boss with the arc length being nearly 1000mm and the wall thickness being 500mm, the shape is complex, the requirements on flaw detection and performance are high, and few domestic enterprises can successfully manufacture the forging.

Because the arc length and the diameter are both extremely large and the opening of a forging press is insufficient, the traditional free forging enterprises divide the arc forging into a plurality of sections and weld a plurality of thin plates together to form the whole arc forging.

The Chinese patent application: 202110007388.8 discloses a forming method and a forming die of an arc forging with a special-shaped cross section, wherein the forming method of the arc forging with the special-shaped cross section comprises upsetting in a die to form a blank, and manufacturing a formed blank by stainless steel ingots in a mode of upsetting in the die; hot extrusion forming, namely performing hot extrusion on the formed blank to form a forging with a rectangular section, taking out the forging with the rectangular section, and performing water cooling, wherein the hot extrusion ratio is not lower than 4; forming a moulding bed, namely forming the moulding bed on the water-cooled forging at the temperature of 1030-1050 ℃ to form the forging with the special-shaped section; and bending and forming, wherein the special-shaped section forging is subjected to bending and forming and post-treatment in sequence to obtain the special-shaped section arc forging. This patent adopts hot extrusion forming to improve the compactness of forging, and every position deflection and deformation condition are unanimous, carries out the child mould after hot extrusion forming and takes shape, has improved material utilization and production efficiency, and furthest has remain the forging fiber streamline, has improved forging mechanical properties.

The Chinese patent application: 201310681435.2 discloses a method for accurately controlling, forming and forging the bending radian of a large arc-shaped forging blank, which skillfully combines free forging and die forging, the forging blank is placed between an upper die (1) with an arc-shaped boss and a lower die (2) with a trapezoidal groove (4) as a cavity, the upper die (1) is driven by a forging hammer to press the bending point of the forging blank (2) downwards for bending forging, and the bending forging is completed when the forging blank (2) contacts the lower surface of the trapezoidal groove (4); the heights of the short sides and the long sides of the trapezoid grooves (4) of the lower forming die (2) are determined according to the required bending radian and length of the forging stock. The bending forming of the arc-shaped forge piece is realized through the tire membranes; the bending radian size of the large arc-shaped forging stock is accurately controlled, the forging heat number is reduced, and the structural performance stability of the large forging piece is improved.

However, the above patent methods are either complex in method and high in process cost, or the quality of the prepared products is not high. Therefore, the invention starts from the shape characteristics of the arc-shaped forge piece, develops the integral forming forging process by designing a special tool, improves the forging rheology of the forge piece, ensures the forging texture of the product, improves the quality of the forge piece product, not only obviously improves the material utilization rate, but also can ensure the continuous forging texture of the forge piece. The forging method and the forming die for the extra-large-diameter thin-wall arc-shaped forging with the boss are not reported at present.

Disclosure of Invention

The invention aims to provide a forging method and a forming die of an oversized-diameter thin-wall arc-shaped forging piece with a boss aiming at the defects of the prior art.

In order to achieve the purpose, the invention adopts the technical scheme that:

the invention provides a forging method of a super-large-diameter thin-wall arc-shaped forging with a boss, which comprises the following steps:

(1) A square billet making stage; in the stage, after the steel ingot is subjected to integral upsetting and drawing at a large deformation rate for 2 times, drawing by adopting upper and lower flat anvils to obtain a step square billet; it should be noted that, for the convenience of subsequent deformation, the edge angle of the blank needs to be chamfered, the bevel angle is 45 degrees, H/2 is larger than or equal to 200mm (H is the thickness of the square blank, the chamfer angle is set based on simulation, when a triangular section is formed by a flat square when the chamfer angle is smaller than 200mm, the edge is easy to be locally deformed and cracked, the quality of the square blank is calculated based on the quality of a forged piece product, meanwhile, the section size is set, the section size of the square blank is 2000 × 1000mm, and the length is 7000 mm), and the square blank with a boss area and a non-boss area has higher concentricity in the length direction, so that the square blank with the shape as shown in fig. 2 is finally obtained.

(2) A step of changing the square billet into a triangular billet; placing the square billet in a special triangular upper die and a special triangular lower die, wherein the schematic position diagram of the dies and the square billet is shown in figure 3, and drawing the square billet section by section into a triangular billet which is shown in figure 4; there are 3 points in the process that need to be particularly noted:

(1) the anvil connection problem of the triangular blank drawing is that in order to ensure the linearity of the blank, the anvil feeding amount is not more than 2a/3 (a is the thickness of a triangular die) each time;

(2) in order to reduce the forming risk of the subsequent procedures, the triangular blank formed by the step square blank and the triangular blank formed by the non-step square blank should also keep higher concentricity in the length direction, and the two triangular shapes have geometric similarity;

(3) the cross section of the triangular blank is an isosceles triangle, wherein the angle alpha of a non-isosceles angle is 45 degrees, the triangular blank is required to be rounded, and the radius R of the rounded angle is about 200mm.

(3) Trapezoidal blank takes shape the stage, adopts last flat stock, presses the apex angle of isosceles triangle base, obtains as the cross section that figure 5 shows is isosceles trapezoid's blank, and during trapezoidal blank preparation, there are 4 key points:

(1) a flat anvil is adopted to press the triangle with the section to the trapezoid height to obtain a blank with the isosceles trapezoid section, at the moment, the forging flow rate of the area close to the upper edge of the trapezoid is fast, the areas, close to the upper edge, of the two waistlines of the trapezoid are locally protruded, and in order to eliminate the deformation of the areas and ensure the isosceles trapezoid, the triangle die in the second step is adopted for local trimming;

(2) controlling the height of the trapezoid cross section of the blank, namely pressing the flat anvil to the height B4 of the trapezoid, wherein the height B4 of the trapezoid is about 1200mm;

(3) the problem of anvil connection of a blank with a trapezoid cross section is solved, in order to ensure the linearity of the blank, the anvil feeding amount is not more than 2b/3 (b is the thickness of a flat anvil) each time;

(4) in order to reduce the forming risk of the subsequent process, the trapezoidal section blank in the step area and the trapezoidal section blank in the non-step area should keep higher concentricity in the length direction, and the heights of the two trapezoidal sections are the same.

(4) A final forming stage, namely pressing two waists of the trapezoidal section blank by adopting a flat anvil, wherein the schematic diagram of the relative positions of the flat anvil and the blank is shown in fig. 6; when rolling deformation, because trapezoidal upper and lower terminal surface forges the difference of flow variable volume, be close to the regional forging of trapezoidal base and flow the grow for the rectangular blank of trapezoidal cross-section takes place to buckle at length direction, finally realizes the shaping of arc forging, and this process has 3 key points:

(1) the upper flat anvil is connected with the anvil and is in relative position relation with the long strip blank, and the upper flat anvil needs to form a certain angle beta with the long strip blank with a trapezoidal section when rolling, wherein the angle beta is more than or equal to 20 degrees and less than or equal to 25 degrees, considering the influence of the friction resistance between the surface of the upper anvil and the long strip blank on the arc deformation of the blank;

(2) in the final forming process, rolling for 3 times along the length direction of the forging stock, wherein the rolling reduction of the first time and the second time is 300mm respectively, and the rolling reduction of the third time is 270mm, and after the measurement meets the size requirement of the arc-shaped forging, finishing to realize the integral forming of the thin-wall arc-shaped forging (shown in figure 7); the rolling reduction is set by considering the forging deformation which can be realized by each fire, and can be executed by 3 times of fire when rolling is actually manufactured by 3 times of rolling, so that the straight trapezoidal section is changed into the arc-shaped flat square section. The heights of the bosses and the non-bosses are the size requirements of the forged product. The triangular die is a special die designed for realizing the forming from flat square to triangle, the key parameters are that the vertex angle alpha of the triangle is 45 degrees +/-3 degrees, the thickness is 1000-1600 mm, other sizes can be enlarged and reduced, and the triangular die only needs to wrap 2000 multiplied by 1000mm flat square to form a triangle with the height of 1500mm.

(3) Rolling and forming a step area of the arc forging, wherein firstly, rolling and forming are carried out from one end of a trapezoidal section blank one by one according to an anvil connecting sequence, and the trapezoidal section at the step is rolled and formed when reaching the step area; during rolling, the contact area of the lug boss and the upper anvil is controlled at the center of the upper anvil, so that one anvil can complete the rolling at the same time.

The triangular die is prepared by forging and forming a square forging stock from a blank and then machining the square forging stock.

The invention has the advantages that:

the invention solves the problem of forging and forming the ultra-large diameter thin-wall arc forging with the boss and designs the corresponding forming die. The required thin-wall arc forging piece is finally formed by bending a long strip through a square section blank (square blank), chamfering, triangular section blank manufacturing, trapezoid section blank pressing and trapezoid two isosceles corners pressing in a final forming stage and through the difference of forging rheology of the upper side and the lower side of the trapezoid section blank. The method has the most obvious technical effect that a forging with continuous integral forging texture can be obtained on the basis of ensuring the shape and the size of the forging through a series of simple free forging operations, and the product quality is obviously improved.

The invention solves the manufacture of the super large diameter thin-wall arc forging with the lug boss, the biggest difficulty of the forging is arc, because the arc has large diameter (generally more than 15000 mm), very thin (not more than 300 mm) and wide (15000-20000 mm), the direct adoption of stamping forming is impossible, and the working size of a common free forging press is exceeded, the design is that the rolling is carried out on the trapezoidal section, and because the forging deformation of the upper and lower trapezoids is different, the deformation of the lower bottom is large, the forging flow is more, the straight-section trapezoid is changed into arc, and the straight-section trapezoid is basically changed into semicircle after 3 times of rolling back and forth.

Generally, free forging is easy to prepare square-section blanks, but it is difficult to directly prepare trapezoidal-section blanks, so that an arc forging can be obtained on the basis of ensuring excellent product performance by adopting a method of preparing the square-section blanks to the triangular blanks and then the triangular-section blanks to the trapezoidal blanks.

Drawings

FIG. 1 is a schematic size diagram of a 120 ton electroslag ingot.

FIG. 2 is a dimensional schematic of a stepped square cross-section billet.

FIG. 3 is a schematic view showing the relative positions of the triangular-section forming die and the square billet.

Figure 4 is a dimensional schematic of a stepped triangular cross-section billet.

Figure 5 is a schematic representation of the dimensions of a stepped isosceles trapezoidal cross-section billet.

Fig. 6 is a schematic diagram of the relative positions of the upper anvil, the trapezoidal cross-section blank and the lower anvil during the final forming stage.

FIG. 7 is a schematic representation of the final formed forging.

FIG. 8 is a scanning electron micrograph of the grain size of the product of example 1.

Detailed Description

The present invention will be further described with reference to the following embodiments. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Furthermore, it should be understood that various changes and modifications can be made by those skilled in the art after reading the disclosure of the present invention, and equivalents fall within the scope of the appended claims.

Example 1

Forging is carried out by adopting a ten thousand ton press, an upper die, a lower die, an upper flat anvil and a lower flat anvil of a special triangular blank in different working procedures, so as to realize the forming of the thin-wall arc-shaped forge piece, and the method comprises the following steps:

step one, preparing a blank, namely after 2 times of compaction operation of large deformation rate integral upsetting and drawing out of the steel ingot in the figure 1, putting the steel ingot into a furnace, keeping the temperature at 1180-1220 ℃, taking the steel ingot out of the furnace after 20 +/-2 hours, drawing out a square section of 2000 multiplied by 1000mm, and chamfering 200mm to obtain the square section step blank shown in the figure 2.

And step two, after the square cross-section step blank is fed into a furnace and subjected to heat preservation at 1180-1220 ℃ for 10 +/-2 hours, placing the square blank into a special triangular upper die and a special triangular lower die, wherein the reduction amount of each anvil is 200mm, the feeding amount of each anvil is 500mm, and the square blank is pressed for 3 times until the height of B2 in the figure 4 is 1500mm, so that the square blank is drawn into a triangular blank, as shown in figure 4.

And step three, after the step blank with the triangular section enters the furnace and is subjected to heat preservation at 1180-1220 ℃ for 9 +/-2 h, pressing the vertex angle of the isosceles triangular blank by using an upper flat anvil until the height B4 of the trapezoid is 1200mm, and obtaining the blank with the isosceles trapezoid cross section as shown in the figure 5.

Step four, after the trapezoid cross section step blank enters the furnace and is subjected to heat preservation at 1180-1220 ℃ for 11 +/-2 hours, two waists of the trapezoid cross section blank are pressed by adopting a flat anvil, and a schematic diagram of the relative positions of the flat anvil and the blank is shown in figure 6; the angle beta between the upper anvil and the strip billet with the trapezoidal section is 20 degrees during rolling, the rolling is performed for 3 times along the length direction of the forging billet, the rolling reduction of the first time and the second time is 300mm respectively, the rolling reduction of the third time is 270mm, and when the step area is pressed, the center of the anvil is consistent with the center of the boss in a control plan view, so that the boss is guaranteed to be rolled by only one anvil during each rolling, after the rolling is completed for three times, whether the size of the arc forging piece meets the requirement is measured, and the integral forming of the thin-wall arc forging piece is realized if the requirement is met (shown in figure 7).

The result is shown in figure 8, the grain size of the product is more than 5 grades, and the yield strength and the tensile strength at room temperature exceed the assessment value by 50 percent.

The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and additions can be made without departing from the principle of the present invention, and these modifications and additions should also be regarded as the protection scope of the present invention.

Claims

1. The forging method of the ultra-large diameter thin-wall arc-shaped forging with the boss is characterized by comprising the following steps of:

(1) A square billet making stage;

(2) A step of changing the square billet into a triangular billet;

(3) Forming a trapezoid blank;

(4) And (5) a final forming stage.

2. The method according to claim 1, wherein step (1) is specifically: firstly, the steel ingot is subjected to 2 times of large deformation rate integral upsetting and drawing-out, then upper and lower flat anvils are adopted for drawing-out to obtain a step square blank, and finally the edge angles of the step square blank are beveled to obtain a square blank.

3. The method according to claim 2, wherein the bevel angle of the chamfer is 45 °, H/2 is not less than 200mm, the chamfer angle of 200mm is set based on simulation, when a triangular section is formed by a flat square, the corner is easy to be locally deformed and cracked, wherein H is the thickness of a step square blank, the quality of the square blank is calculated based on the quality of a forged piece product, and the section size is set, wherein the section size of the square blank is 2000 x 1000mm, and the length is 7000mm.

4. The method according to claim 2, wherein step (2) is specifically: the square billet is placed between a triangular upper die and a triangular lower die, the square billet is drawn into the triangular billet section by section, wherein the triangular die is a square forging billet obtained by forging and forming the billet, and the square forging billet is prepared by adopting a machining mode.

5. The method of claim 4, wherein in the process of drawing the square billet into the triangular billet section by section, the anvil feeding amount is less than or equal to 2a/3 each time in order to ensure the linearity of the billet, wherein a is the thickness of the triangular die.

6. The method as claimed in claim 4, further comprising rounding off the square billet in the process of drawing the square billet into a triangular billet section by section, wherein the cross section of the triangular billet is an isosceles triangle, the vertex angle of the isosceles triangle is 42-48 degrees, no specific requirement on the circular arc angle of the triangle exists, the triangle is smoothly transited to a non-edge angle, and the height of the triangle is 1500mm.

7. The method according to claim 1, wherein step (3) is specifically: and pressing the vertex angle of the isosceles triangular blank by using an upper flat anvil to obtain the trapezoidal blank.

8. The method as claimed in claim 7, wherein the height of the section of the trapezoid blank is 1200mm, the triangular reduction is 300mm, the length of the upper bottom edge of the obtained trapezoid is about 300mm, and the requirement of the final thickness of a forged product is met; the included angle between the two sides of the trapezoid is 42-48 degrees, wherein the anvil feeding amount of each time needs to be less than or equal to 2b/3, and b is the thickness of the flat anvil.

9. The method according to claim 1, characterized in that step (4) is in particular: the two waists of the trapezoidal section blank are pressed by the flat anvil, when rolling deformation occurs, due to the difference of forging flow variables of the upper end face and the lower end face of the trapezoid, the forging flow is increased in the area close to the bottom edge of the trapezoid, so that the strip-shaped blank with the trapezoidal section is bent in the length direction, and finally the arc-shaped forging piece is obtained through forming.

10. The method of claim 9 wherein in the final forming stage, the forging stock is rolled in 3 passes along its length at respective reductions of 300, 300 and 270mm, the upper anvil being at an angle β to the bar of trapezoidal cross section wherein 20 ° β 25 °.