Integral top cover forge piece and forming method and forming tool thereof

Abstract

The invention relates to an integral top cover forge piece and a forming method and tool thereof, and belongs to the technical field of forging. The integral top cover forge piece forming method comprises the steps that a steel ingot is subjected to upsetting and cogging, a circular-truncated-cone-shaped material blank is manufactured, the diameter of the large end of the material blank is d1, and the diameter of the small end of the material blank is d2; after the blank is heated, an annular belt is formed at the small end, the inner diameter of the annular belt is d3, and the outer diameter of the annular belt is d4; after the material blank is heated, the annular belt on the material blank is placed in the groove of the forming bottom pad, then the large end of the material blank is concaved, a forging stock is manufactured, the diameter of a concave baffle is D1, the depth of the concave baffle is delta H1, and the outer diameter of the forging stock is D2; roughly machining the forging stock; and punching is conducted, the machined forging stock is heated, a concave baffle of the forging stock is placed on a lower forming die, then the forging stock is pressed downwards through an upper forming die, the pressing amount is delta H2, and the whole top cover forging piece is manufactured. The forming method effectively solves the near-net forming problem of the whole top cover forge piece with the complex shape, effectively reduces the production cost and improves the quality.

Description

Technical Field

[0001] The invention relates to the technical field of forging, and in particular to an integral top cover forging, a forming method thereof and a forming tool. Background Art

[0002] With the increasing attention paid to green development internationally and the proposal of domestic carbon peak and carbon neutrality goals, green energy has developed rapidly. Nuclear power, as an important green energy, has developed by leaps and bounds. An important development direction of nuclear reactor technology is the integration of nuclear power main forgings. The integrated development of nuclear power forgings helps to reduce the time for nuclear power shutdown and in-service inspection and improve the safety of nuclear reactors.

[0003] The integral top cover forging is an integrated forging in the nuclear reactor pressure vessel. It is composed of the original top head and top cover flange forgings into one forging, which reduces a weld and improves the safety and economy of the nuclear reactor. The large integral top cover forging with stacking nozzle is a type of integral top cover forging with a complex structure and greater difficulty in forming. At present, this type of forging is mainly formed by die forging, which has a large machining allowance and requires more fires to complete the concave opening during forming. The area of ​​the billet that has not been deformed is easily coarse in grain size after repeated high-temperature heating, which reduces the performance of the forging. Therefore, this forming method has high production costs and poor forging performance.

[0004] Therefore, there is an urgent need for a forming method and a forming tooling to achieve a near-net forming method for large and complex integral top cover forgings with pipe connections. Summary of the invention

[0005] In view of the above analysis, the present invention aims to provide an integral top cover forging and a forming method and forming tooling thereof, which can successfully produce large and complex integral top cover forgings with connecting pipes, with small processing allowance and high production efficiency.

[0006] In a first aspect, the present invention provides a method for forming an integral top cover forging, comprising the following steps:

[0007] S1: The steel ingot is roughened and blanked to obtain a truncated cone-shaped blank, the diameter of the large end of the blank is d1, and the diameter of the small end of the blank is d2;

[0008] S2: open ring belt, after heating the blank, open the ring belt on the small end, the inner diameter of the ring belt is d3, and the outer diameter of the ring belt is d4;

[0009] S3: concave opening, after heating the blank, the ring band on the blank is placed in the annular groove of the forming base, and then the large end of the blank is concavely opened to obtain a forging blank, the diameter of the concave is D1, the depth of the concave is ΔH1, and the outer diameter of the forging blank is D2;

[0010] S4: machining, rough machining of forging blank;

[0011] S5: Punching, heating the processed forging blank, placing the concave portion of the forging blank on the forming lower die, and then using the forming upper die to press the forging blank downward by an amount of ΔH2 to obtain an integral top cover forging.

[0012] Furthermore, the height of the annular belt is 80-120 mm.

[0013] Furthermore, in step S5, the heating temperature is 950-1050°C.

[0014] Furthermore, the integral top cover forging The top is equipped with multiple stacking nozzles, and the delivery weight is ≥82t.

[0015] In a second aspect, the present invention provides an integral top cover forging, which is prepared by the forming method of the present invention.

[0016] In a third aspect, the present invention provides a forming tool for implementing the forming method of the present invention, wherein the forming tool comprises a forming base pad, a forming upper die and a forming lower die.

[0017] Furthermore, the formed base pad is in a pancake shape, and an annular groove is opened in the center of the formed base pad. The annular groove is trapezoidal, the width at the narrowest point of the bottom is 10mm larger than the width of the ring belt, the inclination angle is 3°-5°, and the height of the annular groove is consistent with the height of the ring belt.

[0018] Furthermore, the forming upper die is a circular ring, the surface of the lower part of the forming upper die in contact with the blank is an inclined surface with an inclination angle of 5±0.5°, and the radius of the inclined surface and the inner wall of the forming upper die is R200-R250.

[0019] Furthermore, the lower forming mold is in the shape of a hemispherical body with a hollow interior, and the lower forming mold is integrally formed or assembled.

[0020] Furthermore, the forming lower die is assembled and formed from top to bottom, including a first steel plate, a second steel plate, a first circle and a second circle.

[0021] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0022] 1. The present invention adopts the steps of roughing, blanking, ring opening, concave opening, processing and punching of steel ingots, and manufactures the integral top cover forging with the assistance of a forming base pad, a forming lower die and a forming upper die, which effectively solves the problem of near-net forming of the integral top cover forging with complex shapes, effectively reduces production costs and improves product quality.

[0023] 2. Place the ring belt in the annular groove of the forming base, and use a round hammer to make a concave opening on the large end of the blank. During the concave opening process, the ring belt fills the annular groove, and the size and shape of the ring belt can be adjusted and fixed to ensure the formability of the ring belt.

[0024] 3. During the punching process, the forging blank is placed on the hemispherical forming lower die, and then the forging blank is pressed down by the forming upper die. The lower part of the forming upper die is a sloped surface and rounded corner structure. During the punching process, an inward force is applied to the blank to make the blank's external dimensions more accurate.

[0025] 4. The lower die of the present invention can be integrally formed or assembled, and from top to bottom, it is composed of the first steel plate, the second steel plate, the first circle and the second circle, and the first steel plate, the second steel plate, the first circle and the second circle are fixedly connected by vertical pins and horizontal pins. The assembled lower die has a short production cycle and is more flexible, and is suitable for integral top cover forgings of various specifications.

[0026] 5. The forming method and forming tool of the present invention can be used to prepare various specifications of stacking pipes, and the center line of the stacking pipe can be perpendicular to the tangent of any arc surface on the top of the top cover forging.

[0027] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0029] Figure 1 It is a schematic diagram of the integral top cover forging;

[0030] Figure 2 It is a schematic diagram of the blank;

[0031] Figure 3 is a schematic diagram of the open-loop belt process;

[0032] Figure 4 is a schematic diagram of a formed base pad;

[0033] Figure 5 is a schematic diagram of a combined formed base pad;

[0034] Figure 6 It is a schematic diagram of the process of opening a concave gear;

[0035] Figure 7 is a schematic diagram of the forging blank after processing;

[0036] Figure 8 is a schematic diagram of the forming upper die;

[0037] Fig. 9 is a schematic diagram of the forming lower die;

[0038] Fig.10 It is a schematic diagram of the punching process;

[0039] Fig.11 is a schematic diagram of the top cover forging obtained after punching;

[0040] Fig.12 This is a schematic diagram of the fetal membrane forging process of Comparative Example 1;

[0041] In the figure, 1, top cover flange; 2, top head; 3, stacking pipe; 4, forming bottom gasket; 41, first circular ring; 42, second circular ring; 43, third circular ring; 5, forming upper die; 6, forging blank; 7, forming lower die; 8, pad; 101, first steel plate; 102, second steel plate; 103, first circle; 104, second circle; 105, vertical pin; 106, horizontal pin. DETAILED DESCRIPTION

[0042] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0043] Reference Figure 1 The top cover forging is one of the important parts of nuclear power equipment, mainly including the top cover 2, the top cover flange 1 and the stack test pipe 3 fixed on the top cover 2. The original method mainly welds the two forgings of the top cover 2 and the top cover flange 1 through welding process, but the service life of the welded top cover forging is short. In order to improve the safety and economy of the top cover forging and extend the service life, the welded top cover forging is prepared into an integral top cover forging.

[0044] At present, the forming of integral top cover forgings mainly adopts the die forging method, but it has a large processing allowance and a long production cycle. Moreover, as the weight of the top cover forgings gradually increases, the die forging method requires greater pressure for forming, and has higher requirements on equipment.

[0045] Therefore, the present invention provides an integral top cover forging and a forming method thereof, comprising the following steps:

[0046] S1: The steel ingot is roughened and blanked to obtain a truncated cone-shaped blank, the diameter of the large end of the blank is d1, and the diameter of the small end of the blank is d2;

[0047] S2: open ring belt, after heating the blank, open the ring belt on the small end, the inner diameter of the ring belt is d3, and the outer diameter of the ring belt is d4;

[0048] S3: concave opening, after heating the blank, the ring band on the blank is placed in the annular groove of the forming base, and then the large end of the blank is concavely opened to obtain a forging blank, the diameter of the concave is D1, the depth of the concave is ΔH1, and the outer diameter of the forging blank is D2;

[0049] S4: machining, rough machining of forging blank;

[0050] S5: Punching, heating the processed forging blank, placing the concave portion of the forging blank on the forming lower die, and then using the forming upper die to press the forging blank downward by an amount of ΔH2 to obtain an integral top cover forging.

[0051] Compared with the prior art, the forming method provided by the present invention includes the steps of roughing and blanking the steel ingot, opening the ring band, opening the recess, processing and punching. In the process of punching, a forming base pad with an annular groove is used to protect the ring band, and the stacking pipe on the top of the top cover forging is successfully prepared. In the punching stage, a forming lower die and a forming upper die are used, and an inward force is applied to the blank during punching to make the outer dimensions of the blank more accurate. The integral top cover forging is obtained by the forming method provided by the present invention, which effectively solves the problem of near-net forming of integral top cover forgings with complex shapes, reduces the processing amount, and improves material utilization, reduces production costs, and improves product quality.

[0052] Reference Figure 2 In step S1, the steel ingot is heated and then roughed to obtain a truncated cone-shaped blank, the large end diameter of the blank is d1, and the small end diameter of the blank is d2. The integral top cover forging is in the shape of a large top and small bottom concave pit. The steel ingot is roughed to obtain a blank with a large top and small bottom, which is convenient for subsequent forging and can make the shape of the final integral top cover forging more accurate.

[0053] Specifically, the height of the annular belt is 80-120 mm.

[0054] Reference Figure 3 In step S2, the blank is heated, and a round hammer is used to press down the small end of the blank to obtain an annular band, and the height of the annular band is in the range of 80-120 mm. When the height of the annular band is lower than 80 mm, it cannot be guaranteed that the annular groove of the forming base pad 4 will be filled in the subsequent concave opening process, resulting in a problem of material shortage; when the height of the annular band is higher than 120 mm, the diameter of the end of the blank is too large, resulting in waste.

[0055] Reference Figure 4 and Figure 6In step S3, under the action of the round hammer and the forming pad 4, the large end of the heated billet is concave. The ring band on the small end of the billet is placed in the annular groove of the forming pad 4, and then the large end of the billet is concave under pressure by using the round hammer. The forged billet 6 obtained after concave has an outer diameter of D2, a concave diameter of D1, and a concave depth of ΔH1. During the concave process, the forming pad 4 can protect the ring band from forming, ensure the size of the ring band, and then ensure the forming of the stacking pipe 3 in the integral top cover forging.

[0056] Reference Figure 7 In step S4, the present invention performs processing before punching to facilitate the subsequent punching operation. A small boss matching the positioning groove of the forming lower die 7 is arranged at the middle position of the bottom of the concave gear. In the subsequent punching process, the small boss is placed in the positioning groove of the forming lower die 7, which mainly plays the role of positioning and limiting to ensure the forming accuracy.

[0057] Specifically, in step S5, the heating temperature is 950-1050°C.

[0058] When the heating temperature is too high, the grains inside the billet will grow significantly, which is not conducive to the performance of the final integral top cover forging; when the heating temperature is too low, the deformation resistance of the billet will be too large during punching, the size after forming will be poor, and it is easy to cause cracks in the integral top cover forging.

[0059] Reference Figure 8 and Fig. 9 In step S5, the processed forging blank 6 is punched out using the forming upper die 5 and the forming lower die 7, and the small boss in the middle of the bottom of the processed recess is placed in the positioning groove of the forming lower die 7 to ensure that the central axis of the processed forging blank 6 coincides with the central axis of the forming lower die 7; then the forming upper die 5 is placed on the side of the forging blank 6 away from the forming lower die 7, and the central axis of the forming upper die 5 coincides with the central axis of the forging blank 6.

[0060] Reference Fig.10 Under the action of the hydraulic press, the forging blank 6 is continuously pressed down until the concave portion of the forging blank 6 fits against the outer wall of the forming lower die 7, with a pressing amount of ΔH2. After punching, fine processing is performed according to requirements, and different specifications and quantities of stacking pipes 3 are processed on the ring belt.

[0061] Reference Fig.11 By using the forming method provided by the present invention, an integral top cover forging can be prepared, and the outer diameter of the open end is ≥φ5250mm, and the top is provided with multiple stacking pipes 3, the delivery weight is ≥82t, the overall processing amount is small, the preparation cycle is short, and the production efficiency is high.

[0062] A forming tool for implementing the forming method comprises a forming base 4, a forming upper die 5 and a forming lower die 7.

[0063] Reference Figure 4 Specifically, the forming base pad 4 of the present invention is in the shape of a round pancake, and the diameter of the forming base pad 4 is larger than the diameter of the small end of the blank. An annular groove is provided at the center of the forming base pad 4, the width of the annular groove is larger than or equal to the width of the annular belt, and the inner diameter of the annular groove is equal to the inner diameter of the annular belt. The depth of the annular groove is larger than or equal to the height of the annular belt, which can ensure the formability of the stacking tube 3 in the later processing process.

[0064] Preferably, the annular groove of the axial cross-section of the forming base pad 4 is an inverted trapezoid, which ensures that the metal at the bottom of the blank fills the annular groove and facilitates the blank to separate from the forming base pad 4.

[0065] Preferably, the annular groove is in an inverted trapezoidal shape, the width of the narrowest part of the bottom is 10 mm larger than the width of the ring belt, the inclination angle is 3°-5°, and the height of the annular groove is consistent with the height of the ring belt.

[0066] Reference Figure 5 Preferably, a first circular ring 41, a second circular ring 42 and a third circular ring 43 are arranged in sequence from the outside to the inside in the annular groove, and the inner side surface of the first circular ring 41, the top surface of the second circular ring 42 and the outer side surface of the second ring form a second annular groove, and the cross-section of the second annular groove is a trapezoid.

[0067] The first circular ring 41 and the third circular ring 43 are respectively located on the inner wall of the annular groove, and the second circular ring 42 is located between the first circular ring 41 and the third circular ring 43 and located on the bottom surface of the annular groove. The forming base pad 4 in the present invention can form second annular grooves of different specifications through the composition of the first circular ring 41, the second circular ring 42 and the third circular ring 43, and is thus suitable for annular belts of different specifications.

[0068] Reference Figure 8 The forming upper die 5 is a circular ring, and the surface of the lower part of the forming upper die 5 that contacts the blank is an inclined surface with an inclination angle of 5±0.5°, and the radius of the inclined surface and the inner wall of the forming upper die 5 is R200~R250.

[0069] The angle of the forming upper die 5 is to apply force from the outside to the inside to the forging blank 6 during punching. When the angle is too large, the forging blank 6 will shrink prematurely, causing the forging blank 6 to fit with the forming lower die 7 too early and generate friction, resulting in insufficient height dimension of the forging blank 6, which cannot meet the requirements of the top cover forging; when the angle is too small, the forging blank 6 cannot fit with the forming lower die 7 during punching, resulting in a larger inner cavity size of the forging blank 6, which cannot meet the inner cavity processing size of the top cover forging.

[0070] Reference Fig. 9 Specifically, the lower forming mold 7 is a hemispherical shape with a hollow interior, and the lower forming mold 7 can be integrally formed or assembled.

[0071] When the forming lower die 7 is integrally formed, it is mainly prepared by combining casting and machining. The forming lower die 7 is relatively stable as a whole, but its preparation cycle is relatively long, which prolongs the preparation cycle of the integral top cover forging.

[0072] Specifically, the forming lower die 7 is assembled and comprises, from top to bottom, a first steel plate 101, a second steel plate 102, a first circle 103 and a second circle 104. The first steel plate 101, the second steel plate 102, the first circle 103 and the second circle 104 are fixedly connected by vertical pins 105 and horizontal pins 106, and may also be fixedly connected by welding.

[0073] In the present invention, the first steel plate 101 is a solid structure surrounded by a plane and an arc surface, the plane is circular, the arc surface is an arc surface, and a positioning groove for inserting a small protrusion is provided at the center of the arc surface. The second steel plate 102 is a solid structure surrounded by an upper plane, a lower plane and an arc surface, the upper plane and the lower plane are circular, and the upper end surface of the second steel plate 102 is equal to the lower end surface of the first steel plate 101.

[0074] The first circle 103 is a truncated cone as a whole, and a cylindrical through groove is opened at the center of the first circle 103, which saves materials while ensuring strength, and the upper end surface of the first circle 103 is equal to the lower end surface of the second steel plate 102. The second circle 104 is a truncated cone structure with a hollow interior, and the upper and lower planes are both circular, and the upper end surface of the second circle 104 is equal to the lower end surface of the first circle 103, and the height of the second circle 104 is greater than the height of the first circle 103.

[0075] In a possible embodiment, the forming lower die 7 may also be composed of two parts, wherein the first steel plate 101 and the second steel plate 102 are integrally formed as a part of the forming lower die 7, and the first circle 103 and the second circle 104 are integrally formed as another part of the forming lower die 7.

[0076] Reference Fig. 9 A positioning groove is provided at the center of the outer peripheral surface of the first steel plate 101 to facilitate the insertion of the small boss in the middle of the bottom of the concave block after processing, so as to ensure that the central axis of the forging blank 6 coincides with the central axis of the forming lower die 7 after processing. The assembled forming lower die can be replaced with the first steel plate 101, the second steel plate 102, the first circle 103 or the second circle 104 to meet the sizes of the concave blocks of different top cover forgings.

[0077] In order to more clearly describe the present invention, it is further illustrated by the following examples and comparative examples.

[0078] Example 1

[0079] A certain project has an integral top cover forging with a pipe connection. The outer diameter of the opening end of the forging is about φ5250mm, with 12 stacking pipes on the top, and the height of the forging is about 2200mm.

[0080] The forming process of the integral top cover forging is as follows:

[0081] S1: Use 290t steel ingot for overall upsetting, then single-side upsetting with a height of 500mm to obtain a truncated cone-shaped billet, the large end diameter d1 of the billet is 4800mm±100mm, and the small end diameter d2 of the billet is 4100mm±100mm;

[0082] S2: Open-loop belt: Place the billet with the small end facing upward into a heating furnace for heating at a temperature of 1250±10°C; take the billet out of the heating furnace, place it on a rotary table and press it down by 100mm with a hammer to open the small end of the billet into an upper open-loop belt. The inner diameter d3 of the ring belt is 2350mm, the outer diameter d4 of the ring belt is 3350mm, and the height is 100mm;

[0083] S3: concave: place the round pancake-shaped forming pad on the turntable, the diameter of the forming pad is 6000mm, and the height h1 is 500mm; put the billet into the heating furnace with the large end facing upward for heating, and the heating temperature is 1250±10℃; place the heated billet on the forming pad, so that the ring belt is placed in the annular groove of the forming pad, and use a round hammer to concave the large end of the billet, the concave diameter D1 is 4100~4250mm, the depth ΔH1 is 600~750mm, and the outer diameter D2 of the forging billet is 5750~5850mm;

[0084] S4: Processing: Process the ring band of the enveloping stacking pipe on the forging billet; machine the billet to the required slab size, and a small boss in the middle of the bottom of the concave gear, the diameter of the small boss is 300mm;

[0085] S5: Punching: Assemble the forming lower die, connect the first steel plate, the second steel plate, the first circle and the second circle with vertical pins and horizontal pins, and place the forming lower die on the pad after assembly; and install the forming upper die on the hydraulic press through the connecting frame, the forming upper die is a circular ring, and the surface of the lower part of the forming upper die that contacts the blank is an inclined surface with an inclination angle of 5±0.5°, and the radius of the inclined surface and the inner wall of the forming upper die is R200.

[0086] The processed forging billet is heated to a temperature of 1000±10°C; the forging billet is taken out of the heating furnace and placed on the forming lower die, wherein the small boss in the forging billet is placed in the upper positioning groove of the forming upper die; the forming lower die and the billet are moved to the inside of the hydraulic press and centered, and then punched. After the forming upper die contacts the billet, the pressing amount ΔH2 is 1150mm. Finally, a stacking pipe is machined at the ring belt position, and fine-tuned to obtain an integral top cover forging.

[0087] Comparative Example 1

[0088] The patent application number is 201310496348.X. The integral top cover forging is prepared using 360t steel ingots. Fig.11 The preparation process generally includes: placing a cylindrical blank in a forming lower die, wherein the internal shape and size of the forming lower die are consistent with the external shape and size of the integral top cover;

[0089] Upsetting the blank as a whole until it is flush with the upper end surface of the forming lower die;

[0090] The forming lower die is placed on a rotary table, and a strip hammer is used to rotate and concave (the size of the strip hammer is consistent with the size of the inner cavity of the overall top cover) to produce the finished product.

[0091] Performance Testing

[0092] The integral top cover forgings obtained in Example 1 and Comparative Example 1 were tested, mainly including material utilization, preparation cycle and strength test, and the specific test results are shown in Tables 1-3. The straight section at the bottom of the integral top cover is called the flange, the inner side of the flange is the inner surface, and the outer side is the outer surface. The top of the upper spherical shell is the dome, the inside of the dome is the inner surface, and the outside is the outer surface. T / 2 is the middle part of the wall thickness of the sampling position.

[0093] Table 1 Test results

[0094] Group Example 1 Comparative Example 1 Ingot weight 290t 360t Delivery weight 82t 82t Material utilization 28.28％ 22.78％ Preparation cycle 16 days 25 days

[0095] Table 2 Yield strength test results

[0096]

[0097] Table 3 Tensile strength test results

[0098]

[0099] With reference to Example 1 and Comparative Example 1 and in combination with Tables 1-3, it can be seen that the forming method provided by the present invention, in combination with the forming tooling, can successfully prepare integral top cover forgings of complex shapes, with a short preparation cycle, and significantly improved material utilization compared with the existing method, effectively reducing production costs. The yield strength and tensile strength of the obtained integral top cover forgings are improved compared with the top cover forgings prepared by the existing method.

[0100] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for forming an integral top cover forging, characterized in that: The following steps are involved: S1: The steel ingot is roughened and blanked to obtain a truncated cone-shaped blank, the diameter of the large end of the blank is d1, and the diameter of the small end of the blank is d2; S2: open ring belt, after heating the blank, open the ring belt on the small end, the inner diameter of the ring belt is d3, and the outer diameter of the ring belt is d4; S3: concave opening, after heating the blank, the ring band on the blank is placed in the annular groove of the forming base, and then the large end of the blank is concavely opened to obtain a forging blank, the diameter of the concave is D1, the depth of the concave is ΔH1, and the outer diameter of the forging blank is D2; S4: machining, rough machining of forging blank; S5: Punching, heating the processed forging blank, placing the concave portion of the forging blank on the forming lower die, and then using the forming upper die to press the forging blank downward by an amount of ΔH2 to obtain an integral top cover forging.

2. The integral top cover forging forming method according to claim 1, characterized in that: The height of the annular belt is 80-120 mm.

3. The integral top cover forging forming method according to claim 1, characterized in that: In step S5, the heating temperature is 950-1050°C.

4. The integral top cover forging forming method according to claim 1, characterized in that: The outer diameter of the opening end of the integral top cover forging is ≥φ5250mm, and the top is provided with a plurality of stacking pipes, and the delivery weight is ≥82t.

5. An integral top cover forging, characterized in that: The method is prepared by the forming method according to any one of claims 1 to 4.

6. A forming tool for implementing the forming method according to any one of claims 1 to 4, characterized in that: The forming tool comprises a forming base, a forming upper die and a forming lower die.

7. The forming tool according to claim 6, characterized in that: The formed base pad is in the shape of a round pancake, and an annular groove is opened in the center of the formed base pad. The annular groove is trapezoidal, the width of the narrowest part of the bottom is 10mm larger than the width of the ring belt, the inclination angle is 3°-5°, and the height of the annular groove is consistent with the height of the ring belt.

8. The forming tool according to claim 6, characterized in that: The forming upper die is a circular ring, and the surface of the lower part of the forming upper die that contacts the blank is an inclined surface with an inclination angle of 5±0.5°, and the radius between the inclined surface and the inner wall of the forming upper die is R200-R250.

9. The forming tool according to claim 6, characterized in that: The lower forming mold is in the shape of a hemispherical body with a hollow interior, and the lower forming mold is integrally formed or assembled and molded.

10. The forming tool according to claim 9, characterized in that: The lower forming die is assembled and formed, and from top to bottom are the first steel plate, the second steel plate, the first circle and the second circle.

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