Punching and grinding combined forming method for upper end socket forge piece for evaporator of national and No.1 nuclear power unit

Abstract

The invention provides a punching and rolling combined forming method of an upper end socket forge piece for an evaporator of a national and No.1 nuclear power unit, which comprises the following steps of: prefabricating a three-step plate blank: the diameter D1 of a first step is the limit forging size of forging equipment, the diameter D2 of a second step is 0.6-0.75 D1, the diameter D3 of a third step is equal to D pipe nozzle + 100mm, the height H1 of the first step is 400mm, and the height H2 of the third step is equal to 400mm; the height H2 of the second step is equal to 300mm according to the constant volume principle and computer simulation, and the height H3 of the third step is equal to Hnozzle; a plate blank with a positioning boss is manufactured, specifically, the positioning boss is arranged on the face, making contact with the mold, of the three-step plate blank, and the diameter of the positioning boss is matched with that of a mold groove; an upper die groove and a positioning boss are adopted for positioning, the pre-punching height is controlled to be 0.5-0.7 h forge pieces, and preliminary size control is completed; the second step is rolled and expanded through an arc-shaped rolling upper anvil, the rolling reduction of the first circle is 40-50 mm, the rolling reduction of the subsequent pass is 70-90 mm, and the total rolling reduction reaches 0.8-0.9 H1; the final rolling reduction is controlled to be within the range of h-1. 1 h, and precise size control is achieved through die shrinkage. According to the technical scheme, near-net forming of the large upper end socket forge piece can be achieved.

Description

Technical Field

[0001] This invention belongs to the field of metal material forming, and more specifically, relates to a stamping and rolling combined forming method for the upper end forging of the evaporator of the "Guohe-1" nuclear power unit. Background Technology

[0002] The CAP1400 evaporator is a key piece of equipment in my country's independently designed "Guohe-1" nuclear power unit, characterized by its large-scale design, high heat exchange efficiency, and safety and reliability. Currently, the CAP1400 evaporator forgings designed and constructed mostly adopt an integrated design, making them the largest in size among reactor types currently under construction, and their complex shapes present significant challenges in forming.

[0003] The specific structure of the upper head forging of the CAP1400 evaporator is as follows: Figure 1 As shown, this upper head forging consists of an upper part of the upper head and an upper head ring. It has a more complex shape and a larger opening diameter than traditional upper heads. The maximum height of the upper head is approximately 2100mm, the opening diameter exceeds Φ6500mm, the inner spherical radius exceeds SR5500mm, and the slab unfolded size exceeds φ8000mm. These dimensions exceed the forging limits of most domestic forging equipment, therefore it cannot be formed by rough machining of a pre-cast slab followed by stamping. Summary of the Invention

[0004] In view of this, the present invention provides a method for stamping and rolling forming of the upper end forging for the evaporator of the "Guohe-1" nuclear power unit.

[0005] The stamping and rolling combined forming method of the present invention is used for near-net-shape forming of the upper head forging of "Guohe No. 1", and specifically includes the following steps:

[0006] Precast three-step slab: the diameter D1 of the first step is the limit forging dimension of the forging equipment; the diameter D2 of the second step is 0.6 to 0.75D1; the diameter D3 of the third step is D... 管嘴 +100mm, the height of the first step H1 = 400mm, the height of the second step is derived from the principle of constant volume and computer simulation, and the height of the third step H3 = H 管嘴 ;

[0007] To produce a slab with a positioning boss: a positioning boss is provided on the side of the three-step slab that contacts the mold, and the diameter of the positioning boss matches the groove of the mold.

[0008] Pre-stamping: The upper die groove and positioning boss are used for positioning. The pre-stamping height is controlled at 0.5~0.7h forging, and the initial size control is completed.

[0009] Local compaction and diameter expansion: Use an arc-shaped compaction anvil to compact and expand the diameter of the second step. The compaction amount of the first pass is 40-50 mm, and the compaction amount of subsequent passes is 70-90 mm, with a total compaction amount of 0.8-0.9H1.

[0010] Integral shrinkage forming: The final reduction is controlled within h to 1.1h of the forging, and precise dimensional control is achieved through die shrinkage.

[0011] The beneficial effects of this invention are as follows:

[0012] The present invention discloses a combined stamping and rolling forming method for the upper head forging of the evaporator of the "Guohe-1" nuclear power unit. This method employs a process of "pre-fabricated three-step slab with allowance + slab pre-stamping + partial rolling and diameter expansion of the slab + integral die closing forming," successfully solving the manufacturing bottleneck of the "Guohe-1" upper head forging due to insufficient dimensional limits of existing forging equipment. This solution utilizes a three-stage coordinated control: first, pre-stamping of the three-step slab with positioning bosses to initially control the forging dimensions; second, using zoned rolling technology to achieve curved surface diameter expansion; and finally, precise control of the forging dimensions through closing forming. By implementing this technical solution, near-net-shape forming of the "Guohe-1" upper head forging has been achieved, providing a reliable technical guarantee for the localization of key components in third-generation nuclear power.

[0013] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0014] The present invention can be better understood by referring to the following description taken in conjunction with the accompanying drawings, in which the same or similar reference numerals are used throughout the drawings to denote the same or similar parts.

[0015] Figure 1 A schematic diagram of the structure of the "Guohe No. 1" upper head forging according to an embodiment of the present invention is shown;

[0016] Figure 2 A flowchart illustrating the implementation of a stamping and rolling combined forming method for the upper end forging of the evaporator of the "Guohe-1" nuclear power unit according to an embodiment of the present invention is shown.

[0017] Figure 3 A schematic diagram of the near-net-shape structure of the "Guohe No. 1" upper head forging according to an embodiment of the present invention is shown;

[0018] Figure 4 A schematic diagram of an elliptical end cap and its dimensions according to an embodiment of the present invention is shown;

[0019] Figure 5 A schematic diagram of the structure of a three-step slab according to an embodiment of the present invention is shown;

[0020] Figure 6 A schematic diagram of the structure of the upper die for punching according to an embodiment of the present invention is shown;

[0021] Figure 7 A schematic diagram of the structure of the lower die for punching according to an embodiment of the present invention is shown;

[0022] Figure 8 The structural schematic of the rolling anvil according to an embodiment of the present invention is shown;

[0023] Figure 9 A schematic diagram of the pre-flush process according to an embodiment of the present invention is shown;

[0024] Figure 10 A schematic diagram illustrating the matching of the billet and the die during the rolling process according to an embodiment of the present invention is shown;

[0025] Figure 11 A schematic diagram of the rolling process according to an embodiment of the present invention is shown;

[0026] Figure 12 A schematic diagram of the closing process according to an embodiment of the present invention is shown. Detailed Implementation

[0027] To enable those skilled in the art to more fully understand the technical solutions of the present invention, exemplary embodiments of the present invention will be described more comprehensively and in detail below with reference to the accompanying drawings. Obviously, the one or more embodiments of the present invention described below are merely one or more specific ways to implement the technical solutions of the present invention, and are not exhaustive. It should be understood that other ways belonging to a general inventive concept can be used to implement the technical solutions of the present invention, and should not be limited to the embodiments described exemplary. Based on one or more embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0028] Example: Figure 2 A flowchart illustrating the implementation of the stamping and rolling combined forming method for the upper end forging of the evaporator of the "Guohe-1" nuclear power unit according to an embodiment of the present invention is shown. (Refer to...) Figure 2 The stamping and rolling forming method for the upper end forging of the evaporator of the "Guohe-1" nuclear power unit according to an embodiment of the present invention includes the following steps:

[0029] Precast three-step slab: the diameter D1 of the first step is the limit forging dimension of the forging equipment; the diameter D2 of the second step is 0.6 to 0.75D1; the diameter D3 of the third step is D... 管嘴 +100mm, the height of the first step H1 = 400mm, the height of the second step is derived from the principle of constant volume and computer simulation, and the height of the third step H3 = H管嘴 ;

[0030] To produce a slab with a positioning boss: a positioning boss is provided on the side of the three-step slab that contacts the mold, and the diameter of the positioning boss matches the groove of the mold.

[0031] Pre-stamping: The upper die groove and positioning boss are used for positioning. The pre-stamping height is controlled at 0.5~0.7h forging, and the initial size control is completed.

[0032] Local compaction and diameter expansion: Use an arc-shaped compaction anvil to compact and expand the diameter of the second step. The compaction amount of the first pass is 40-50 mm, and the compaction amount of subsequent passes is 70-90 mm, with a total compaction amount of 0.8-0.9H1.

[0033] Integral shrinkage forming: The final reduction is controlled within h to 1.1h of the forging, and precise dimensional control is achieved through die shrinkage.

[0034] This invention provides a stamping and rolling combined forming scheme for the upper head forging of the "Guohe-1" shipwreck. The scheme employs a technical approach of "pre-fabricated three-step slab with allowance + slab pre-stamping + partial rolling and diameter expansion of the slab + integral die closing forming" to achieve near-net-shape forming of the "Guohe-1" upper head forging. The specific solution is as follows:

[0035] Step 1: Design the forging drawing. Figure 1 This is a structural schematic diagram of the forged head of the "Guohe-1" ship, and also a delivery drawing. Figure 1 Based on the delivery drawing shown, considering sampling and hot working allowances, and after reasonably filling the forging allowance, the following is obtained: Figure 3 The forging drawing shown is a near-net-shape structural diagram of the upper head forging of "Guohe-1".

[0036] Step 2: Slab Design. The slab design process is as follows: Calculate the required slab dimensions (diameter × thickness) for integral stamping. Considering the maximum forging dimensions achievable by the forging equipment, stack the remaining material on top of the first step with the largest outer diameter to form a second step. Add a boss nozzle to the two aforementioned slab steps to obtain the final slab. Figure 5 The three-step slab structure shown.

[0037] Figure 4 A schematic diagram of the elliptical head and its dimensions is shown. (Refer to...) Figure 4 and Figure 5 If this upper head forging is formed by stamping, the required slab diameter is:

[0038]

[0039] in,

[0040]

[0041] The volume of the stamped slab can be calculated from this:

[0042]

[0043] Volume of slab produced by a combination of stamping and rolling:

[0044]

[0045] Based on computer numerical simulation results, metal flow trends, and billet burn-off, the volume of the stamping process is V2≈1.05~1.1V1. The diameter D1 of the first step is taken as the limit forging dimension of the forging equipment, and the slope transition angle θ=130~140°. The diameter D of the second step... 2＝ The best forming effect of rolling diameter development is achieved when the value is between 0.6 and 0.75D1.

[0046] Step 3: Design the mold.

[0047] 1) Design of the upper die for stamping: such as Figure 6 The outer contour of the upper die shown is the same as the inner cavity contour of the forging drawing, i.e., SR 冲型上模 =SR 内 The height h1 of the stamping die should be greater than h. 锻件 The diameter d of the groove in the upper stamping die 凹槽 =D 凸台 +100~120mm.

[0048] 2) Design of the lower die for stamping: Figure 7 A schematic diagram of the lower die for punching is shown. (Refer to...) Figure 7 The diameter D of the lower die of the stamping type 61 =D1+100~200mm, the internal space design should be based on the principle of accommodating the nozzle space during punching and taking into account the allowable limit of punching deviation of the end cap allowance, D6≥D 管嘴 +200mm; Inner end face radius R 61 R100 to R200 is typically set; SR is determined based on the shrinkage pattern of the rolled billet after stamping. 61 =1.05SR outer + 20-40mm, mold height H 61 ≥H 锻件 .

[0049] 3) Design the compaction mold;

[0050] The design of the anvil for rolling: such as Figure 8The outer contour of the rolling anvil shown is the same as the inner cavity contour of the forging drawing, i.e., R7 = SR_outer. Based on the load distribution characteristics of 140MN during the rolling process and the requirement that the flow of metal along the arc length and circumference during the rolling process must meet the dimensions of the forging billet before stamping and closing, the arc length of the rolling anvil is L = D2 + 200 - 300 mm, the lower width of the anvil is B1 = 400 - 600 mm, the upper width is B2 = B1 + 300 - 500 mm, and the thinnest part of the anvil in the height direction is ≥ 900 mm. Based on the shape characteristics of the rolling die and the flow law of the metal during the rolling process in this die, L1 = D 管嘴 +200~250mm, h1=H 管嘴+ 150~200mm.

[0051] Step 4: Pre-forming the slab. Through multiple upsetting, drawing, and backing processes using conventional forging techniques, a uniform and dense slab is pre-formed. Figure 5 The three-step slab shown has a maximum outer diameter D1 of approximately φ7400mm, which is the limit size of the forging equipment, and D2 = 0.6~0.75D1.

[0052] Step 5: Perform pre-punching. (Press...) Figure 9 As shown, the assembly mold is used to pre-stamp the slab. In the forging diagram, boss D is a positioning boss that fits into the groove designed in the upper mold and is used for auxiliary positioning of the pre-stamping. The stamping height is approximately 0.5 to 0.7h. After the stamping is completed, a turning tool is used to turn the pre-stamped slab over so that the bowl face is down and the boss nozzle is up. The slab is then returned to the furnace for heat preservation.

[0053] Step 6: Perform localized rolling and diameter expansion of the slab. According to... Figure 10 and Figure 11 As shown, place the blank and the mold, and place the upper stamping die upside down on the turntable. Use clamps to place the pre-stamped slab blank after the heat preservation is completed on the upside-down upper stamping die, so that the inner cavity boss of the forging is aligned with the groove of the upper stamping die for positioning.

[0054] The upper anvil contacts the upper die, setting it as the zero point for compaction. Compact to 0.8–0.9H1, in 5–6 passes. After each anvil press, rotate the turntable 7–10°, rotating 180° per pass. Therefore, the turntable is expected to rotate 18–25 times per pass. The first pass is mainly to ensure the billet fits the lower die (i.e., the upper stamping die), so the compaction amount should not be too large. The recommended compaction amount for the final pass is 40–50 mm. From the second to the last pass, the compaction amount can be appropriately increased to approximately 70–90 mm. Compaction stops when the target dimension of 0.8–0.9H1 is reached. Figure 5In the three-step slab diagram shown, after the second step is rolled by the anvil, the billet metal flows in the diameter direction, and the diameter of the curved surface increases. When the rolling workload is large and cannot be completed in one firing cycle, it can be returned to the furnace for appropriate heat preservation according to the billet equivalent before being rolled again. After rolling, a turning fixture is used to turn the billet so that the bowl-shaped end faces upwards when it enters the furnace, followed by heating and heat preservation.

[0055] Step 7: Final finishing: According to Figure 12 After mold assembly and heat preservation, use special clamps to hold the billet out of the furnace and place it on the lower mold. When placing it, pay attention to observe that the distance between the rim of the billet and the upper surface of the lower mold in all directions should be approximately equal. As the stroke of the upper mold increases, the rim of the billet gradually shrinks, and the closing step pressing amount is h to 1.1h.

[0056] By rationally designing a three-step slab, the curved surface is extended and the diameter is developed through a "stamping + rolling" method, and finally the pre-set forging shape is obtained by closing the die. By designing positioning bosses on the forging drawing and grooves on the die, the high-precision positioning requirements under complex working conditions are met.

[0057] The following provides a more detailed description of the stamping and rolling combined forming method for the upper end forging of the nuclear power unit evaporator according to a specific example:

[0058] Reference Figure 3 The forging shown has a main dimension of D. 外 =6700mm, D 内 =6000mm, H 锻件 =2500mm, h=2000mm, H 管嘴 =450mm, D 管嘴 =2000mm, SR 内 =5500mm, SR 外 Taking 5850mm as an example, the specific solution is as follows:

[0059] Step 1: The slab stamping thinning rate is generally 0.1 to 0.2, here we take 0.12, the slab thickness is (6700-6000) / ((1-0.12)*2)≈400mm;

[0060] According to the formula for the development of an elliptical head, if slab stamping is used for forming, the slab diameter is approximately φ8100mm, and the slab weight G1 = 8.1. 2 *6.165*0.4+2 2 *6.165*0.65=172.9t;

[0061] G2 = 1.05G1 = 181.5t;

[0062]

[0063] The main dimensions are: D1 = 7400, H1 = 400, D3 = 0.68D1≈5030mm, H2 = 300mm; D2 = 4400mm, H3 = 200mm, and the transition angle θ = 136°.

[0064] Step 3: Design the mold.

[0065] 1) Design of the upper die for stamping: SR 冲型上模 =SR outer = 5850mm, upper mold height is selected as 2000mm, upper mold diameter is selected as 5900.

[0066] 2) Design of the lower die for stamping: D 61 ≥D1=7400mm, select D 61 =7500mm, d6=2800mm, SR 61 =SR 外 =5850mm, lower die height =3000mm, fillet radius R between upper plane and inner spherical surface 61 Take 250mm.

[0067] 3) Design of the rolling anvil: The arc profile of the rolling anvil is the same as the arc plane profile of the outer curved surface of the forging, therefore R7 = SR 外 =5850mm, L1 is selected as 2200mm, h1 is selected as 550mm, and B1 is selected as 600mm.

[0068] Step 4: Pre-fabrication of three-step slabs. Pre-fabrication of slabs. Through conventional forging methods such as multiple upsetting, drawing, and upsetting peeling, pre-fabricate three-step slabs with uniform and dense structure. The maximum outer diameter D1 is taken as the limit dimension of the forging equipment, approximately φ7400mm. The main dimensions are set as D1 = 7400mm and H1 = 400mm.

[0069] Step 5: Pre-stamping. Align the upper and lower dies beforehand, place the slab on the lower die, and ensure the groove of the upper die aligns with the protrusion on the slab. The stroke of the pre-stamping is 1400mm. After pre-stamping, use a flipping fixture to flip the slab so that the bowl-shaped opening faces down before entering the furnace.

[0070] Step 6: Rolling. Invert the aforementioned upper die on the turntable. Place the slab onto the upper die, ensuring the bowl-shaped opening of the slab is approximately horizontal and not tilted. Roll using the rolling anvil. For the first pass, reduce the blank size by 40mm. Before the next pass, rotate the turntable approximately 8°. Increase the reduction to 80mm for each subsequent pass. Roll for a total of 6 passes. Stop rolling when the thickness is approximately H1 = 400mm. After rolling, use a turning fixture to flip the slab so the bowl-shaped opening faces upwards for easier finishing in the next firing.

[0071] Step 7: Finishing the opening. Align the upper and lower dies in advance, use clamps to place the blank on the lower die of the stamping mold, control the horizontality of the bowl edge, and press down vertically with the upper die of the stamping mold. The pressing amount for the finishing pass is 2000mm.

[0072] This invention provides a forming scheme combining stamping and rolling for the upper head forging of "Guohe No. 1". It adopts a process of "pre-made three-step slab with allowance + slab pre-stamping + slab local rolling and diameter expansion forming + integral mold closing forming", which successfully solves the manufacturing bottleneck caused by insufficient limit size of forging equipment and realizes near-net-shape forming of upper head forging.

[0073] While one or more embodiments of the present invention have been described above, those skilled in the art will recognize that the present invention can be implemented in any other form without departing from its spirit and scope. The embodiments described above are illustrative and not restrictive, and many modifications and substitutions will be apparent to those skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A method for forming a forged upper head for the evaporator of the "Guohe-1" nuclear power unit by a combination of stamping and rolling, characterized in that, include: Precast three-step slab: the diameter D1 of the first step is the limit forging dimension of the forging equipment; the diameter D2 of the second step is 0.6 to 0.75D1; the diameter D3 of the third step is D... 管嘴 +100mm, the height of the first step H1 = 400mm, the height of the second step is derived from the principle of constant volume and computer simulation, and the height of the third step H3 = H 管嘴 ; To produce a slab with a positioning boss: a positioning boss is provided on the side of the three-step slab that contacts the mold, and the diameter of the positioning boss matches the groove of the mold. Pre-stamping: The upper die groove and positioning boss are used for positioning. The pre-stamping height is controlled at 0.5~0.7h forging, and the initial size control is completed. Local compaction and diameter expansion: Use an arc-shaped compaction anvil to compact and expand the diameter of the second step. The compaction amount of the first pass is 40-50 mm, and the compaction amount of subsequent passes is 70-90 mm, with a total compaction amount of 0.8-0.9H1. Integral shrinkage forming: The final reduction is controlled within h to 1.1h of the forging, and precise dimensional control is achieved through die shrinkage.

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