A method for expanding a hole of an ultra-thick cylinder forging

Abstract

The application discloses a kind of methods for reaming of super-thick cylinder forgings, belong to the field of forging, solve the problem of complex reaming process of existing super-thick cylinder forgings. Including: the mandrel is inserted into the inner diameter of the cylinder blank, then placed on the horse frame, the cylinder blank is placed on the first step or the third step;After the lower part of the hammer head is aligned with the cylinder blank, press down the reaming hammer head to ream;Lift the reaming hammer head, rotate the mandrel, drive the cylinder blank to rotate, repeat step 2;Repeat step 3 until the gap between the cylinder blank and the moving platform is 50mm-100mm;Lift the reaming hammer head, move the cylinder blank to the second step;After aligning the reaming hammer head with the cylinder blank, press down the reaming hammer head to ream;Lift the reaming hammer head, rotate the mandrel, drive the cylinder blank to rotate, repeat step 6;Repeat step 7 until the cylinder blank reaches the target size, and obtain the super-thick cylinder forging. The method of the application can produce super-thick cylinder forgings with high quality and high efficiency.

Description

Technical Field

[0001] This invention relates to the field of forging technology for ultra-large and extra-thick cylindrical forgings, and particularly to a method for expanding the hole in ultra-large and extra-thick cylindrical forgings. Background Technology

[0002] Under the goal of green and low-carbon development, my country's energy industries, such as petrochemicals and nuclear power, are showing a trend towards large-scale development. To adapt to the needs of the energy industry and improve equipment performance and safety, pressure equipment is gradually developing towards larger diameters and thicker walls. With the increasing diameter and wall thickness of key components like cylinder forgings, existing forging methods can no longer meet the goals of mass production and high efficiency. Especially during the process of expanding the cylinder hole to produce the finished product, the height of the forging frame needs to be adjusted to achieve the final forming, which not only affects manufacturing efficiency but also negatively impacts the quality of the cylinder due to repeated reheating. Summary of the Invention

[0003] In view of the above, the present invention aims to provide a method for expanding the hole of ultra-large and extra-thick cylindrical forgings, which solves the problems of complex and inefficient existing hole expansion processes for ultra-large and extra-thick cylindrical forgings. The method of the present invention can produce ultra-large and extra-thick cylindrical forgings with high efficiency.

[0004] The objective of this invention is mainly achieved through the following technical solutions: This invention provides a method for expanding the hole of an ultra-large and extra-thick cylindrical forging. The method employs a hole-expanding mold, which includes an expanding hammer, a frame, and a lever. The expanding hammer is a combined structure, comprising an upper part, a lower part, a hydraulic cylinder, and a connecting shaft. One end of the upper part is connected to the lower part via the connecting shaft, and the other end is connected to one end of the hydraulic cylinder. The other end of the hydraulic cylinder is connected to the lower part of the hammer. The opening and closing angle between the upper and lower parts is controlled by the extension and retraction of the hydraulic cylinder. The lever is a stepped shaft structure, comprising a first step, a second step, and a third step connected in sequence. The diameters of the first and third steps are both D31, and the diameter of the second step is D32, where D32 > D31. The method for expanding the hole of ultra-large and extra-thick cylindrical forgings includes the following steps: Step 1: After heating and keeping the cylindrical billet warm, insert the lever into the inner diameter of the cylindrical billet, and then place the lever on the frame, with the cylindrical billet placed on the first or third step; the frame is placed on a moving platform. Step 2: After aligning the lower part of the hammer head with the cylinder blank, start the press to press down the expanding hammer head to expand the hole; Step 3: Raise the reaming hammer, operate the machine to hold the lever and rotate it, causing the cylinder billet to rotate 10° to 20°. Then repeat step 2 to ensure that the rotation angle is uniform until one revolution is completed. Step 4: Repeat step 3 until the gap between the cylinder blank and the moving platform reaches S1, where S1 is 50mm~100mm. Step 5: Raise the reaming hammer and move the cylinder blank to the second step; Step 6: After aligning the reaming hammer with the cylinder blank, start the press and press down the reaming hammer to ream the hole; Step 7: Raise the reaming hammer, operate the machine to hold the lever and rotate it, causing the cylinder billet to rotate 10° to 20°, and then repeat step 6; ensure that the rotation angle is uniform until one revolution is completed. Step 8: Repeat step 7 until the outer diameter and thickness of the cylindrical blank reach the target dimensions to obtain an ultra-large and extra-thick cylindrical forging.

[0005] Furthermore, the length of the second step is L31, and the height of the cylindrical blank is L20, where L31 > L20.

[0006] Furthermore, in step 1, the initial outer diameter D20 of the cylinder blank is ≥7000mm and the initial wall thickness T20 is ≥1500mm.

[0007] Furthermore, in step 2, the reduction amount is controlled to be ≤50mm.

[0008] Furthermore, the end of the cylindrical blank closer to the connecting shaft is the large end, and the end farther from the connecting shaft is the small end. After each reaming, the inner diameter of both ends of the cylindrical blank is measured. If the inner diameters of the two ends of the cylindrical blank are inconsistent, the tilt angle of the lower part of the hammer is adjusted by adjusting the height of the hydraulic cylinder.

[0009] Furthermore, when the inner diameter of the large end of the cylindrical blank is greater than that of the small end, the ejection height of the hydraulic cylinder is increased to increase the tilt angle of the lower part of the hammer head, and then the hole is enlarged; when the inner diameter of the large end of the cylindrical blank is less than that of the small end, the ejection height of the hydraulic cylinder is decreased to decrease the tilt angle of the lower part of the hammer head, and then the hole is enlarged. Furthermore, the relationship between the hydraulic cylinder height adjustment amount ΔH in the horizontal direction and the inner diameter of the large end of the cylinder blank D23 and the inner diameter of the small end of the cylinder blank D24 is ΔH = (0.5~0.7) × |D23-D24|, where |D23-D24| represents the absolute value of D23-D24.

[0010] Furthermore, in step 1, before reaming the hole, the included angle between the upper part of the hammer head and the lower part of the hammer head is 20°~70°.

[0011] Furthermore, in step 2, before reaming, the gap between the reaming hammer head, after being moved to its maximum height, and the upper part of the cylindrical blank is 50mm~100mm.

[0012] Furthermore, in step 6, the reduction amount is controlled to be ≤50mm.

[0013] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects: In the hole enlargement method for ultra-large and extra-thick cylindrical forgings of the present invention, the lever is set as a stepped shaft structure. By enlarging the hole in stages, the technical problem of low efficiency caused by multiple forging operations due to space limitations of forging equipment during hole enlargement of ultra-large and extra-thick cylindrical forgings can be effectively solved.

[0014] In the reaming method for ultra-large and extra-thick cylindrical forgings of the present invention, after each reaming cycle, the inner diameters of the large and small ends of the cylindrical blank are measured, and the tilt angle of the lower part of the hammer head can be dynamically adjusted in real time according to the deviation of the inner diameters at both ends. That is, when the inner diameter of the large end of the cylindrical blank is greater than that of the small end, the ejection height of the hydraulic cylinder is increased, so that the tilt angle of the lower part of the hammer head increases, and then the reaming begins; when the inner diameter of the large end of the cylindrical blank is less than that of the small end, the ejection height of the hydraulic cylinder is decreased, so that the tilt angle of the lower part of the hammer head decreases, and then the reaming begins until the cylindrical blank meets the manufacturing requirements. This method can solve the problem of asynchronous material feeding at both ends of the ultra-large and extra-thick cylindrical forging blank.

[0015] The method of this invention, through the mutual cooperation of molds, dynamically adjusts the tilt angle of the lower part of the hammer in real time, and adopts a step-by-step hole-expanding forging method, which can effectively solve the problem of limited press space for ultra-large and extra-thick cylindrical forgings, as well as the problem of asynchronous material feeding at both ends of the billet during the hole-expanding process, and can achieve high-efficiency forging of ultra-large and extra-thick cylindrical forgings.

[0016] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of what is particularly pointed out in the written description and the accompanying drawings. Attached Figure Description

[0017] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0018] Figure 1 This is a schematic diagram of a hole-reaming hammer. Figure 2 This is a schematic diagram of a horse harness. Figure 3 This is a schematic diagram of the mold and blank before hole enlargement; Figure 4 A schematic diagram showing the reduction of the lower tilt angle of the hammer during hole enlargement; Figure 5 A schematic diagram illustrating the increase in the tilt angle of the lower part of the hammer during hole enlargement; Figure 6 This is a schematic diagram of the mold and blank after the hole enlargement in step 4; Figure 7 This is a schematic diagram of the mold and blank before the hole enlargement in step 5; Figure 8 A schematic diagram showing the reduction of the lower tilt angle of the hammer during hole enlargement; Figure 9 A schematic diagram illustrating the increase in the tilt angle of the lower part of the hammer during hole enlargement; Figure 10 This is a schematic diagram of the mold and blank after the hole enlargement is completed; Figure 11 This is a schematic diagram of the finished forging of the present invention; Figure label: 10. Hole-reducing hammer, 20. Cylindrical blank, 30. Lever, 40. Frame, 11. Upper part of hammer, 12. Lower part of hammer, 13. Hydraulic cylinder, 14. Connecting shaft, 301. First step, 302. Second step, 303. Third step. Detailed Implementation

[0019] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of the present invention and, together with the embodiments of the present invention, serve to illustrate the principles of the present invention.

[0020] This invention provides a method for expanding the hole in ultra-large and extra-thick cylindrical forgings. The method employs a hole-expanding die, such as... Figure 1 and Figure 2 As shown, the reaming mold includes a reaming hammer head 10, a frame 40, and a lever 30. The reaming hammer head is a combined structure hammer head, including an upper part 11, a lower part 12, a hydraulic cylinder 13, and a connecting shaft 14. One end of the upper part 11 is connected to the lower part 12 via the connecting shaft 14, and the other end of the upper part 11 is connected to one end of the hydraulic cylinder 13. The other end of the hydraulic cylinder 13 is connected to the lower part 12. The opening and closing angle between the upper part 11 and the lower part 12 is controlled by the extension and retraction movement of the hydraulic cylinder 13. The lever 30 is a stepped shaft structure, including a first step 301, a second step 302, and a third step 303 connected in sequence. The diameters of the first step 301 and the third step 303 are both D31, and the diameter of the second step 302 is D32, where D32 > D31. The method for expanding the hole of ultra-large and extra-thick cylindrical forgings includes the following steps: Step 1: After heating and holding the cylindrical blank 20 at that temperature, as follows... Figure 3 As shown, the lever 30 is inserted into the inner diameter of the cylindrical blank, and then the lever 30 is placed on the frame 40, wherein the cylindrical blank is placed on the first step 301 or the third step 303; wherein the frame 40 is placed on a moving platform; as shown Figure 3 As shown Step 2: After aligning the lower part 12 of the hammer head with the cylindrical blank 20, start the press to press down the expanding hammer head 10 to expand the hole; Step 3: Raise the reaming hammer 10, operate the machine to hold the lever and rotate it, driving the cylinder blank 20 to rotate 10°~20°. Then repeat step 2 to ensure that the rotation angle is uniform until one revolution is completed. Step 4: Repeat step 3 until the gap between the cylinder blank 20 and the moving platform reaches S1, where S1 is 50mm~100mm. Figure 6 As shown; Step 5: Raise the reaming hammer 10 to move the cylinder blank 20 to the second step 302, as shown. Figure 7 As shown; Step 6: After aligning the reaming hammer 10 with the cylindrical blank 20, start the press and press down the reaming hammer 10 to ream the hole. Step 7: Raise the reaming hammer 10, operate the machine to hold the lever and rotate it, driving the cylinder blank to rotate 10°~20°, and then repeat step 6; ensure that the rotation angle is uniform until one revolution is completed. Step 8: Repeat step 7 until the outer diameter of the cylindrical blank reaches D22 and the thickness reaches T22, completing the forging of the ultra-large and extra-thick cylindrical forging. A schematic diagram of the mold and blank after the hole expansion is shown below. Figure 10 As shown, the finished product of the ultra-large and extra-thick cylindrical forging is as follows: Figure 11 As shown.

[0021] Specifically, the length of the second step 302 is L31, and the height of the cylindrical blank 20 is L20, where L31 > L20.

[0022] Specifically, in step 1 above, the initial outer diameter D20 of the cylindrical blank 20 is ≥7000mm and the initial wall thickness T20 is ≥1500mm.

[0023] Specifically, in step 2, before reaming, the maximum height that the reaming hammer 10 can move upward is H0. After the reaming hammer moves up to the maximum height, the gap S0 between it and the upper part of the cylindrical blank is 50mm~100mm, for example, 50mm, 60mm, 70mm, 80mm, 90mm, 100mm.

[0024] Specifically, in step 2, the pressing amount should be controlled to be ≤50mm, for example, 30~50mm, to avoid the outer circle from folding or the inner hole from being too deep due to excessive pressing amount.

[0025] Specifically, during the hole enlargement process, the increase in the outer diameter of the cylindrical blank causes the gap between the bottom of the cylindrical blank and the moving platform to decrease to S1, which is in the range of 50mm-100mm. Therefore, it is impossible to continue enlarging the hole. So, in order to solve the problem of the small gap S1, step 5 is required.

[0026] Specifically, the end of the cylindrical blank closer to the connecting shaft is defined as the large end, and the end farther from the connecting shaft is defined as the small end. After each reaming, the inner diameters of both ends of the cylindrical blank are measured. If the inner diameters of both ends of the cylindrical blank are inconsistent, the tilt angle of the lower part of the hammer needs to be adjusted by adjusting the height of the hydraulic cylinder.

[0027] Specifically, before the first hole enlargement begins, the included angle between the upper part 11 and the lower part 12 of the hammer head is 20°~70°.

[0028] Specifically, when the inner diameter of the large end of the cylinder blank is larger than the inner diameter of the small end, the thrust height of the hydraulic cylinder is increased, thereby increasing the tilt angle of the lower part of the hammer (e.g., Figure 5 , Figure 9 (As shown), then begin reaming; when the inner diameter of the large end of the cylinder blank is smaller than the inner diameter of the small end, reduce the hydraulic cylinder ejection height to reduce the tilt angle of the lower part of the hammer (as shown). Figure 4 , Figure 8 (as shown in the image), and then begin enlarging the hole.

[0029] Specifically, if the inner diameters at both ends of the cylindrical blank are inconsistent, the relationship between the adjustment amount ΔH of the hydraulic cylinder height based on the horizontal direction and the inner diameters D23 and D24 of the large end of the cylindrical blank is ΔH = (0.5~0.7) × |D23-D24|, where |D23-D24| represents the absolute value of D23-D24.

[0030] Specifically, in step 5 above, the maximum height that the reaming hammer 10 can move upward is H0, and the gap S2 between the reaming hammer and the upper part of the cylinder after moving upward to the maximum height is 50mm~100mm.

[0031] Specifically, in step 6 above, after the expanding hammer comes into contact with the cylinder blank, it expands the hole by pressing down with a set value of ≤50mm to avoid the outer circle from folding or the inner hole from being too deep due to excessive pressing down.

[0032] Specifically, in the above method, the relationship between the initial wall thickness T20 before the borehole expansion of the cylindrical blank, the wall thickness T21 after the borehole expansion in step 4, and the wall thickness T22 after the borehole expansion in step 8 is: T20 > T21 > T22.

[0033] Specifically, in step 8 above, after the hole is enlarged, the gap S3 between the cylinder blank and the moving platform is in the range of 50mm~100mm.

[0034] Specifically, the outer diameter D22 of the finished cylinder obtained in step 8 above is ≥7800mm, and the wall thickness T22 is ≥1250mm.

[0035] In the hole enlargement method for ultra-large and extra-thick cylindrical forgings of the present invention, the lever is set as a stepped shaft structure. By enlarging the hole in stages, the problem of multiple forging operations caused by space limitations of forging equipment during hole enlargement of ultra-large and extra-thick cylindrical forgings can be effectively solved.

[0036] In the reaming method for ultra-large and extra-thick cylindrical forgings of the present invention, after each reaming cycle, the inner diameters of the large and small ends of the cylindrical blank are measured, and the tilt angle of the lower part of the hammer head can be dynamically adjusted in real time according to the deviation of the inner diameters at both ends. That is, when the inner diameter of the large end of the cylindrical blank is greater than that of the small end, the ejection height of the hydraulic cylinder is increased, so that the tilt angle of the lower part of the hammer head increases, and then the reaming begins; when the inner diameter of the large end of the cylindrical blank is less than that of the small end, the ejection height of the hydraulic cylinder is decreased, so that the tilt angle of the lower part of the hammer head decreases, and then the reaming begins until the cylindrical blank meets the manufacturing requirements. This method can solve the problem of asynchronous material feeding at both ends of the ultra-large and extra-thick cylindrical forging blank.

[0037] The method of this invention, through the mutual cooperation of molds, dynamically adjusts the tilt angle of the lower part of the hammer in real time, and adopts a step-by-step hole-expanding forging method, which can effectively solve the problem of limited press space for ultra-large and extra-thick cylindrical forgings, as well as the problem of asynchronous material feeding at both ends of the billet during the hole-expanding process, and can achieve high-efficiency forging of ultra-large and extra-thick cylindrical forgings.

[0038] The advantages of the method of the present invention will be demonstrated below with specific embodiments.

[0039] Example 1 This embodiment provides a method for expanding the hole in an ultra-large and extra-thick cylindrical forging. The method uses a hole-expanding die, such as... Figure 1 and Figure 2 As shown, the reaming mold includes a reaming hammer head 10, a frame 40, and a lever 30. The reaming hammer head is a combined structure, comprising an upper part 11, a lower part 12, a hydraulic cylinder 13, and a connecting shaft 14. One end of the upper part 11 is connected to the lower part 12 via the connecting shaft 14, and the other end is connected to one end of the hydraulic cylinder 13. The other end of the hydraulic cylinder 13 is connected to the lower part 12. The opening and closing angle between the upper part 11 and the lower part 12 is controlled by the extension and retraction of the hydraulic cylinder 13. The lever 30 is a stepped shaft structure, comprising a first step 301, a second step 302, and a third step 303 connected in sequence. The diameters of the first step 301 and the third step 303 are both D31, and the diameter of the second step 302 is D32. Wherein, D31 = 1320 mm and D32 = 1820 mm. The length of the second step 302 is L31=1500mm, and the height of the cylindrical blank is L20=1315mm; The method for expanding the hole of ultra-large and extra-thick cylindrical forgings includes the following steps: After heating and heat preservation of the cylindrical blank 20, insert the lever 30 into the inner diameter of the cylindrical blank, and then place the lever 30 on the frame 40, wherein the cylindrical blank is placed on the first step 301 or the second step 302; wherein the frame 40 is placed on the moving platform; after the reaming hammer is raised to the maximum height, the gap S0 between the lower end face of the reaming hammer and the cylindrical blank is 75mm. First round of reaming: Before the first round of reaming, the lower part of the reaming hammer is adjusted to a horizontal position. The cylindrical blank is placed at the first step of the lever. Before the first round of reaming, the outer diameter of the cylindrical blank is 7070mm and the inner diameter is 4000mm. The reaming reduction is set to 50mm. After the first round of reaming, the inner and outer diameters of both ends of the cylindrical blank are the same, with an outer diameter of 7206mm and an inner diameter of 4236mm. Second round of hole enlargement: After the second round of hole enlargement, the outer diameter of the large end of the cylinder blank is 7300mm and the inner diameter is 4435mm, and the outer diameter of the small end is 7355mm and the inner diameter is 4485mm. Since the inner diameter of the large end is smaller than that of the small end, the hydraulic cylinder ejection height is reduced and adjusted to 30mm. Third round of hole reaming: After the third round of hole reaming, the outer diameter of the large end of the cylinder blank is 7520mm and the inner diameter is 4750mm, and the outer diameter of the small end is 7500mm and the inner diameter is 4730mm. Since the inner diameter of the large end is larger than that of the small end, the ejection height of the hydraulic cylinder is increased by 40mm based on the ejection height of the second round. Fourth enlargement: The press setting line is reduced by 50mm. After the fourth enlargement, the inner diameter of the large end is 4895mm and the outer diameter is 7570mm. The outer diameter of the small end is 7575mm and the inner diameter is 4900mm. The distance of the bottom moving platform of the billet is 65mm. Move the cylinder blank to the second step position and adjust the lower part of the reaming hammer to a horizontal state; Fifth round of reaming: 50mm reduction. After the fifth round of reaming, the outer diameter of the large end of the cylindrical blank is 7800mm and the inner diameter is 5225mm, and the outer diameter of the small end is 7805mm and the inner diameter is 5230mm. This meets the requirements for the finished forging dimensions of 7795mm outer diameter and 5235mm inner diameter, thus completing the forging of the ultra-large and extra-thick cylindrical forging.

[0040] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for expanding the hole in an ultra-large, extra-thick cylindrical forging, characterized in that, The reaming method for the ultra-large and extra-thick cylindrical forging adopts a reaming mold, which includes a reaming hammer (10), a frame (40), and a lever (30). The reaming hammer is a combined structure hammer, which includes an upper part (11), a lower part (12), a hydraulic cylinder (13), and a connecting shaft (14). One end of the upper part (11) is connected to the lower part (12) of the hammer through the connecting shaft (14), and the other end of the upper part (11) is connected to one end of the hydraulic cylinder (13). 3) The other end is connected to the lower part (12) of the hammer head, and the opening and closing angle between the upper part (11) of the hammer head and the lower part (12) of the hammer head is controlled by the extension and retraction movement of the hydraulic cylinder (13); the lever (30) is a stepped shaft structure, the lever (30) includes a first step (301), a second step (302) and a third step (303) connected in sequence, the diameter of the first step (301) and the third step (303) is D31, the diameter of the second step (302) is D32, D32>D31; The method for expanding the hole of the ultra-large and extra-thick cylindrical forging includes the following steps: Step 1: After heating and keeping the cylindrical blank (20) warm, insert the lever (30) into the inner diameter of the cylindrical blank, and then place the lever (30) on the frame (40), wherein the cylindrical blank is placed on the first step (301) or the third step (303); wherein the frame (40) is placed on the moving platform; Step 2: After aligning the lower part (12) of the hammer head with the cylindrical blank (20), start the press to press down the expanding hammer head (10) to expand the hole; Step 3: Raise the reaming hammer (10), and rotate the clamping lever of the operating machine to drive the cylinder blank (20) to rotate 10°~20°. Then repeat step 2 to ensure that the rotation angle is uniform until one revolution is completed. Step 4: Repeat step 3 until the gap between the cylindrical blank (20) and the moving platform reaches S1, where S1 is 50mm~100mm; Step 5: Raise the reaming hammer (10) and move the cylinder blank (20) to the second step (302); Step 6: After aligning the reaming hammer (10) with the cylindrical blank (20), start the press to press down the reaming hammer (10) to ream the hole; Step 7: Raise the reaming hammer (10), and rotate the clamping lever of the manipulator to rotate the cylinder blank by 10° to 20°. Then repeat step 6; ensure that the rotation angle is uniform until one revolution is completed. Step 8: Repeat step 7 until the outer diameter and thickness of the cylindrical blank reach the target dimensions to obtain an ultra-large and extra-thick cylindrical forging. Specifically, the end of the cylindrical blank closer to the connecting shaft is the large end, and the end farther from the connecting shaft is the small end. After each reaming, the inner diameter of both ends of the cylindrical blank is measured. If the inner diameters of the two ends of the cylindrical blank are inconsistent, the tilt angle of the lower part of the hammer is adjusted by adjusting the height of the hydraulic cylinder. When the inner diameter of the large end of the cylindrical blank is greater than that of the small end, the ejection height of the hydraulic cylinder is increased to increase the tilt angle of the lower part of the hammer head, and then the hole is enlarged; when the inner diameter of the large end of the cylindrical blank is less than that of the small end, the ejection height of the hydraulic cylinder is decreased to decrease the tilt angle of the lower part of the hammer head, and then the hole is enlarged. The relationship between the hydraulic cylinder height adjustment ΔH based on the horizontal direction and the inner diameter of the large end of the cylinder blank D23 and the inner diameter of the small end of the cylinder blank D24 is ΔH = (0.5~0.7) × |D23-D24|, where |D23-D24| represents the absolute value of D23-D24.

2. The method for expanding the hole of an ultra-large and extra-thick cylindrical forging according to claim 1, characterized in that, The length of the second step (302) is L31, and the height of the cylindrical blank (20) is L20, where L31 > L20.

3. The method for expanding the hole in an ultra-large, extra-thick cylindrical forging according to claim 1, characterized in that, In step 1, the initial outer diameter D20 of the cylindrical blank (20) is ≥7000mm and the initial wall thickness T20 is ≥1500mm.

4. The method for expanding the hole of an ultra-large and extra-thick cylindrical forging according to claim 1, characterized in that, In step 2, the amount of pressure is controlled to be ≤50mm.

5. The method for expanding the hole of an ultra-large and extra-thick cylindrical forging according to claim 1, characterized in that, In step 1, before the hole is enlarged, the angle between the upper part (11) of the hammer head and the lower part (12) of the hammer head is 20°~70°.

6. The method for expanding the hole of an ultra-large and extra-thick cylindrical forging according to claim 1, characterized in that, In step 2, before reaming, the gap between the reaming hammer head and the upper part of the cylindrical blank is 50mm~100mm after the hammer head is moved to its maximum height.

7. The method for expanding the hole of an ultra-large, extra-thick cylindrical forging according to any one of claims 1 to 6, characterized in that, In step 6, the amount of pressure is controlled to be ≤50mm.

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