Welding-seam-free forming method for inner barrel body of flame barrel

Abstract

The invention discloses a weld-seam-free forming method for an inner barrel body of a flame barrel. The weld-seam-free forming method comprises the following steps that (1) blanking is conducted; 2) stretching for the first time; (3) stretching for the second time; (4) residual edges are cut off; (5) roundness correction; and (6) machining. According to the forming method, weldless forming of the flame tube inner tube body is achieved through two times of stretching forming, the forming thickness is uniform, the quality is good, and the machining quality of the flame tube is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of parts processing, and in particular to a method for forming a flame tube inner cylinder without weld seams. Background Art

[0002] The combustion chamber is an important part of the engine. The combustion chamber is the heart of the engine, participating in combustion and providing kinetic energy. Therefore, the processing quality of the flame tube directly affects the performance of the engine. Figure 2 and Figure 3 As shown, the bottom end is provided with a skirt whose outer diameter gradually increases from top to bottom. In order to improve the performance of the flame tube, the flame tube inner cylinder is best formed without welds. However, under the premise of ensuring the forming quality, the seamless forming of the flame tube inner cylinder is difficult, so a method for seamless forming of the flame tube inner cylinder is designed.

[0003] The flame tube is the main area for fuel combustion and is a component that withstands high temperature and high pressure. The current combustion chamber is mainly manufactured by sheet metal parts, which often involve welding, sheet metal forming, heat treatment, zirconium oxide spraying and other processes. The existing technology mostly uses welding + forming. However, due to restrictions such as operating conditions and design requirements, some flame tubes need to be free of welds to ensure the long life of the flame tube. Summary of the invention

[0004] In view of the above-mentioned defects or deficiencies in the prior art, it is desired to provide a method for seamlessly forming the inner cylinder of a flame tube, which realizes seamlessly forming the inner cylinder of the flame tube through two stretching forming processes, has uniform forming thickness and good quality, and ensures the processing quality of the flame tube.

[0005] The present invention provides a method for forming a flame tube inner cylinder without weld seams, comprising the following steps:

[0006] 1) Cutting and cutting to obtain a circular blank;

[0007] 2) First stretching: the circular blank is stretched by a first stretching die to form a first-stretched blank, and the first-stretched blank is subjected to solution heat treatment; the first-stretched blank is a cylindrical shape with a closed top and an open bottom, the top edge of the first-stretched blank is a first round chamfer, the inner diameter of the first-stretched blank is larger than the inner cylinder of the flame tube, and the height is smaller than the inner cylinder of the flame tube;

[0008] 3) Second stretching, the first-drawn blank is stretched by a second stretching die to form a second-drawn blank, and the second-drawn blank is subjected to solution heat treatment; the second-drawn blank is a cylindrical shape with a closed top and an open bottom, the inner diameter of the second-drawn blank is equal to the inner cylinder of the flame tube, and the second-drawn blank has the same contour as the skirt of the inner cylinder of the flame tube near the bottom;

[0009] 4) Cut off the remaining edges, and cut off the remaining edges at the top and bottom of the second-drawn blank to form the inner cylinder of the flame tube;

[0010] 5) Calibration: Calibrate the roundness of the inner cylinder of the flame tube through the calibration mold;

[0011] 6) Machining: The inner wall of the inner cylinder of the flame tube is expanded and supported by a supporting mold, and then the top end surface and the bottom end surface of the inner cylinder of the flame tube are machined.

[0012] Furthermore, the sum of the radii of the inner cylinder of the flame tube and the first round chamfer is greater than the radius of the first-drawn blank, and the radius of the first round chamfer is 10-15mm.

[0013] Further, the first stretching die includes a first convex die, a first blank holder ring and a first concave die;

[0014] The first punch is cylindrical, and a first round chamfer is provided at the top edge thereof. The outer diameter of the first punch is larger than the inner diameter of the inner cylinder of the flame tube;

[0015] The inner diameter of the first pressure ring is in clearance fit with the outer diameter of the first punch;

[0016] The first die is provided with a first forming hole, and a second round chamfer is provided at the bottom end of the first forming hole.

[0017] Furthermore, before the first-stretched blank is stretched for the second time, an air-eliminating hole is provided on the top end surface thereof.

[0018] Furthermore, the second stretching die includes a second convex die, a stripping ring, a second blank holder ring and a second concave die;

[0019] The second punch is cylindrical, and a third round chamfer is provided on the top edge thereof. The outer diameter of the second punch is equal to the inner diameter of the inner cylinder of the flame tube;

[0020] The stripping ring is detachably sleeved on the bottom end of the second male mold;

[0021] The inner diameter of the second pressure ring is in clearance with the outer diameter of the second punch, and the outer diameter is equal to the inner diameter of the first drawn blank ±0.5 mm. The outer diameter of the top of the second pressure ring gradually decreases from bottom to top to form an inner molding surface of the skirt.

[0022] The second concave die is provided with a second forming hole, and the inner diameter of the bottom end of the second forming hole gradually increases from top to bottom to form an outer forming surface of the skirt.

[0023] Further, the shape correction mold includes a third concave mold, a shape correction component and a shape correction cone;

[0024] The third die is provided with a shaping hole in the vertical direction, the inner diameter of the shaping hole is the same as the outer diameter of the inner cylinder of the flame tube, and the inner diameter of the top end of the shaping hole gradually increases from top to bottom to form a skirt outer shaping portion;

[0025] The shape correction component is annular, and its inner diameter gradually decreases from top to bottom, and its outer diameter is the same as the inner diameter of the inner cylinder of the flame tube, and the outer diameter of the top gradually increases from bottom to top to form a skirt inner shape correction part, and the shape correction component is composed of a plurality of shape correction blocks uniformly distributed along the circumferential direction and wedge blocks respectively arranged between adjacent shape correction blocks, and the cross section of the shape correction block is fan-shaped;

[0026] The outer diameter of the lower part of the correction cone matches the inner diameter of the correction component and gradually decreases from top to bottom.

[0027] Furthermore, the supporting mold includes a base, an expansion support assembly and an expansion cone;

[0028] A column is fixedly arranged on the top of the base;

[0029] The expansion support assembly is arranged on the top surface of the base and is located at the outer periphery of the column. The inner diameter of the expansion support assembly above the column gradually decreases from top to bottom, and its outer diameter is the same as the inner diameter of the inner cylinder of the flame tube. The outer diameter of the expansion support assembly near the bottom end gradually increases from bottom to top to form a skirt expansion part. The expansion support assembly includes a plurality of expansion blocks evenly distributed on the outer periphery of the column, and the cross-section of the expansion block is fan-shaped, and guide countersunk holes are respectively opened on the expansion block along the radial direction of the column, and guide screws pass through the guide countersunk holes one by one and are threadedly connected to the column. A spring for elastically supporting the expansion block is sleeved on the guide screw, and a limiting block is fixedly arranged on the bottom of the expansion block. A limiting ring groove is opened on the top surface of the base at the outer periphery of the column, and the limiting blocks are all embedded in the limiting ring groove to limit the maximum expansion radius of each of the expansion blocks;

[0030] The expansion cone is arranged in the expansion support assembly and is located above the column. The expansion cone is connected to the column through an expansion screw. The outer diameter of the expansion cone gradually decreases from top to bottom to match the inner diameter of the expansion support assembly.

[0031] Compared with the prior art, the beneficial effects of the present invention are:

[0032] When the forming method of the present invention is used to stretch the inner cylinder of the flame tube, the first-stretch blank obtained by the first stretching has a small stretching height and a large diameter, with chamfers at the turns, and the forming material is uniform, avoiding the problem of raw material tearing caused by excessive single stretching; the first-stretch blank is heat-treated to improve plasticity, uniform structure, and eliminate stress; the second stretching is performed to obtain the second-stretch blank, that is, the inner cylinder of the flame tube with excess material, and then heat treatment is performed again to eliminate stress and stabilize the surface and size; the excess material is cut off to obtain the inner cylinder of the flame tube, and then a rounding treatment is performed to solve the problem of the part becoming elliptical when the excess material is cut off; finally, the end face of the inner cylinder of the flame tube is machined to ensure the flatness of the end face and ensure the processing quality when it is subsequently welded with other parts. The forming method of the present application realizes the weld-free forming of the inner cylinder of the flame tube through two stretching forming, and the forming thickness is uniform and the quality is good, ensuring the processing quality of the flame tube.

[0033] It should be understood that the contents described in the summary of the invention are not intended to limit the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0035] Figure 1 It is a flow chart of the method for forming the inner cylinder of the flame tube without weld seams;

[0036] Figure 2 It is a schematic diagram of the structure of the inner cylinder of the flame tube;

[0037] Figure 3 It is a schematic diagram of the cross-sectional structure of the inner cylinder of the flame tube;

[0038] Figure 4 It is a schematic diagram of the structure of a blank;

[0039] Figure 5 It is a schematic diagram of the cross-sectional structure of a blank;

[0040] Figure 6 It is a schematic diagram of the cross-sectional structure of the second-drawn blank;

[0041] Figure 7 is a structural schematic diagram of a first stretching die;

[0042] Figure 8 is a schematic diagram of the exploded structure of the first stretching die;

[0043] Fig. 9 is a schematic diagram of the cross-sectional structure of the first stretching die;

[0044] Fig.10 is a schematic structural diagram of a second stretching die;

[0045] Fig.11 is a schematic diagram of the explosion structure of the second stretching die;

[0046] Fig.12 is a schematic diagram of the cross-sectional structure of the second stretching die;

[0047] Fig.13 It is a structural schematic diagram of the shape correction mold;

[0048] Fig.14 The exploded structure diagram of the shape correction mold;

[0049] Fig.15 Schematic diagram of the cross-sectional structure of the shape correction mold;

[0050] Fig.16 It is a schematic diagram of the structure of the supporting mold;

[0051] Fig.17 A schematic diagram of the explosion structure supporting the mold;

[0052] Fig.18 A schematic diagram of the cross-sectional structure of the supporting mold.

[0053] Numbers in the figure: 1, inner cylinder of flame tube; 2, first stretching die; 3, second stretching die; 4, shape correction die; 5, support die;

[0054] 11. First drawing of blank; 12. Second drawing of blank; 13. Skirt; 15. Air-eliminating hole;

[0055] 21. first convex die; 22. first pressure ring; 23. first concave die; 24. first forming hole;

[0056] 31. second punch; 32. stripping ring; 33. second edge-holding ring; 34. second die; 35. inner molding surface of skirt; 36. second molding hole; 37. outer molding surface of skirt;

[0057] 41. third concave die; 42. shape correction component; 43. shape correction cone;

[0058] 411, shape adjustment hole; 412, outer shape adjustment portion of skirt;

[0059] 421, shape correction block, 422, wedge block; 423, inner shape correction part of skirt;

[0060] 51. Base; 52. Expansion support assembly; 53. Expansion cone; 54. Expansion screw

[0061] 511, column; 512, limiting ring groove;

[0062] 521, expansion block; 522, skirt expansion portion; 523, guide countersunk hole; 524, guide screw; 525, spring; 526, limit block. DETAILED DESCRIPTION

[0063] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It should also be noted that, for ease of description, only the parts related to the invention are shown in the accompanying drawings.

[0064] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0065] Please refer to Figures 1 to 18 The embodiment of the present invention provides a method for forming a flame tube inner cylinder without weld seams, comprising the following steps:

[0066] 1) Cutting and cutting to obtain a circular blank;

[0067] 2) First stretching: the circular blank is stretched by the first stretching die 2 to form a first-stretched blank 11, and the first-stretched blank 11 is subjected to solution heat treatment; the first-stretched blank 11 is a cylindrical shape with a closed top and an open bottom, the top edge of the first-stretched blank 11 is a first round chamfer, the inner diameter of the first-stretched blank 11 is larger than the inner cylinder 1 of the flame tube, and the height is smaller than the inner cylinder 1 of the flame tube;

[0068] 3) Second stretching, the first-drawn blank 11 is stretched by the second stretching die 3 to form a second-drawn blank 12, and the second-drawn blank 12 is subjected to solution heat treatment; the second-drawn blank 12 is a cylinder with a closed top and an open bottom, the inner diameter of the second-drawn blank 12 is equal to the inner cylinder 1 of the flame tube, and the second-drawn blank 12 near the bottom has the same contour as the skirt 13 of the inner cylinder 1 of the flame tube;

[0069] 4) Cutting off the remaining edges, cutting off the remaining edges at the top and bottom of the second-drawn blank 12 to form the inner cylinder 1 of the flame tube;

[0070] 5) roundness calibration: the roundness of the inner cylinder 1 of the flame tube is calibrated by a calibration die 4;

[0071] 6) Machining: The inner wall of the flame tube inner cylinder 1 is expanded and supported by the supporting mold 5, and then the top end surface and the bottom end surface of the flame tube inner cylinder 1 are machined.

[0072] In this embodiment, when the flame tube inner cylinder 1 is stretched, the first stretching blank 11 obtained by the first stretching has a small stretching height and a large diameter, and has a chamfer at the turning point. The forming material is uniform, and the problem of raw material tearing due to excessive single stretching is avoided; the first stretching blank 11 is heat treated to improve plasticity, uniform structure, and eliminate stress;

[0073] Then, the second stretching is performed to obtain the second-drawn blank 12, that is, the flame tube inner cylinder 1 with excess material, and the second-drawn blank 12 is heat-treated to eliminate stress and stabilize the profile and size; the excess material is cut off to obtain the flame tube inner cylinder 1, and then the roundness is corrected to solve the problem of the part becoming elliptical when the excess material is cut off;

[0074] Finally, the end face of the flame tube inner cylinder 1 is machined to ensure the flatness of the end face and the processing quality when it is subsequently welded with other parts. The forming method of the present application realizes the weld-free forming of the flame tube inner cylinder 1 through two stretching forming, and the forming thickness is uniform and the quality is good, which ensures the processing quality of the flame tube.

[0075] In a preferred embodiment, the sum of the radii of the inner cylinder 1 of the flame tube and the first round chamfer is greater than the radius of the first drawn blank 11, so that when the second stretching is performed, the mold is pressed on the first round chamfer and stretching is performed, thereby improving the smoothness of the stretching material; the radius of the first round chamfer is 10-15mm, and the large radius of the first round chamfer is conducive to preventing wrinkles at the edge holding position during the second stretching.

[0076] In a preferred embodiment, if Figure 7 to Figure 9 As shown, the first stretching die 2 includes a first punch 21, a first blank holder ring 22 and a first die 23;

[0077] The first punch 21 is cylindrical, and a first round chamfer is provided at the top edge thereof. The outer diameter of the first punch 21 is larger than the inner diameter of the flame tube inner cylinder 1;

[0078] The inner diameter of the first pressure ring 22 is clearance-matched with the outer diameter of the first punch 21;

[0079] The first die 23 is provided with a first forming hole 24 , and a second round chamfer is provided at the bottom end of the first forming hole 24 .

[0080] In this embodiment, when performing the first stretching, the circular blank is first clamped by the first clamping ring 22 and the first die 23, and then the first clamping ring 22 and the first die 23 are clamped by hydraulic equipment and slowly pressed down, and the first punch 21 passes through the first clamping ring 22 and squeezes the circular blank into the first forming hole 24, completing the stretching forming of the first drawn blank 11.

[0081] The sum of the thickness of the first pressure ring 22 and the height of the inner cylinder 1 of the flame tube is greater than the height of the first punch 21, so that the height of the first-pull blank 11 after forming is smaller than the height of the inner cylinder 1 of the flame tube.

[0082] The rounded chamfered structure design on the first drawing die 2 improves the smoothness of the drawing material; preferably, the edge of the first pressure ring 22 is designed with a step stop, which is convenient for placing the circular blank concentrically with the first drawing die 2 to ensure uniform drawing material. The forming principle of this structure is: the punch is fixed, and the die and the pressure ring press the periphery of the part and move downward together.

[0083] In a preferred embodiment, if Figure 5 As shown, before the second stretching of the first-stretched blank 11, an air-eliminating hole 14 is opened on its top surface, so that the air in the top of the first-stretched blank 11 can be discharged during the second stretching, thereby ensuring the forming quality of the second stretching.

[0084] In a preferred embodiment, if Figure 10 to Figure 12 As shown, the second stretching die 3 includes a second punch 31, a stripping ring 32, a second blank holder ring 33 and a second die 34;

[0085] The second punch 31 is cylindrical, and a third round chamfer is provided at the top edge thereof. The outer diameter of the second punch 31 is equal to the inner diameter of the flame tube inner cylinder 1;

[0086] The stripping ring 32 is detachably sleeved on the bottom end of the second male mold 32;

[0087] The inner diameter of the second pressure ring 33 is in clearance with the outer diameter of the second punch 31, and the outer diameter is equal to the inner diameter of the blank 11 ±0.5mm. The outer diameter of the top of the second pressure ring 33 gradually decreases from bottom to top to form a skirt inner molding surface 35;

[0088] The second die 34 is provided with a second forming hole 36 , and the inner diameter of the bottom end of the second forming hole 36 gradually increases from top to bottom to form a skirt outer forming surface 37 .

[0089] In this embodiment, when the drawn blank 11 is stretched for the second time, the stripping ring 32 is firstly put on the bottom end of the second punch 32; then the drawn blank 11 is put on the second pressure ring 33; preferably, the outer diameter of the second pressure ring 33 is slightly larger than the inner diameter of the drawn blank 11, and it is pressed into the drawn blank 11 by hydraulic equipment, so as to achieve a good expansion and pressure effect.

[0090] Then the second pressure ring 33 is put on the top of the second punch 31, and then the second die 34 is driven to be slowly pressed down by hydraulic equipment. As the second die 34 is pressed down, the second pressure ring 33 slowly moves down until the second-drawn blank 12 is stretched and formed, and the flame tube inner cylinder 1 with residual material is obtained, and the stretching forming quality is good.

[0091] When withdrawing the material, first lift the second die 34, then pass a push rod through the air eliminator 14 and connect it to the top thread of the second punch 31, so as to press the second punch 31; then push the withdrawing ring 32 through the hydraulic equipment, the withdrawing ring 32 pushes the second pressure ring 33 to move up along the second punch 31, and the second pressure ring 33 pushes the second drawn blank 12 to move up to complete the material withdrawal, which is convenient for material withdrawal.

[0092] In a preferred embodiment, if Figure 13 to Figure 15 As shown, the shape correction mold 4 includes a third concave mold 41, a shape correction component 42 and a shape correction cone 43;

[0093] The third die 41 is provided with a shaping hole 411 in the vertical direction. The inner diameter of the shaping hole 411 is the same as the outer diameter of the inner cylinder 1 of the flame tube. The inner diameter of the top of the shaping hole 411 gradually increases from top to bottom to form a skirt outer shaping portion 412.

[0094] The shape correction component 42 is annular, and its inner diameter gradually decreases from top to bottom, and its outer diameter is the same as the inner diameter of the inner cylinder 1 of the flame tube. The outer diameter of the top gradually increases from bottom to top to form a skirt inner shape correction part 423. The shape correction component 42 is composed of a plurality of shape correction blocks 421 uniformly distributed along the circumferential direction and wedge blocks 422 respectively arranged between adjacent shape correction blocks 421. The cross section of the shape correction block 421 is fan-shaped.

[0095] The outer diameter of the lower portion of the shape correction cone 43 matches the inner diameter of the shape correction component 42 and gradually decreases from top to bottom.

[0096] In this embodiment, when the inner cylinder 1 of the flame tube is calibrated, first, the skirt 13 is placed upward into the calibration hole 411, and then the calibration blocks 421 are evenly placed in the inner cylinder 1 of the flame tube, and then the wedge blocks 422 are respectively placed between adjacent calibration blocks 421; at this time, the calibration cone 43 is pressed down by hydraulic equipment, and the calibration cone 43 squeezes the wedge blocks 422, and the wedge blocks 422 squeeze the calibration blocks 421 to expand outward, thereby expanding the inner cylinder 1 of the flame tube from the inside, which solves the problem of the inner cylinder 1 of the flame tube becoming elliptical after the excess edge is cut off, and its roundness is ensured.

[0097] In a preferred embodiment, if Figure 16 to Figure 18 As shown, the supporting mold 5 includes a base 51, an expansion support assembly 52 and an expansion cone 52;

[0098] A column 511 is fixedly provided on the top of the base 51;

[0099] The expansion support assembly 52 is arranged on the top surface of the base 51, and is located at the outer periphery of the column 511. The inner diameter of the expansion support assembly 52 located above the column 511 gradually decreases from top to bottom, and its outer diameter is the same as the inner diameter of the inner cylinder 1 of the flame tube. The outer diameter of the expansion support assembly 52 near the bottom gradually increases from bottom to top to form a skirt expansion part 522. The expansion support assembly 52 includes a plurality of expansion blocks 521 uniformly distributed on the outer periphery of the column 511. The cross section of the expansion block 521 is fan-shaped. The expansion block 521 has radial sections along the column 511. A guide countersunk hole 523 is provided, and a guide screw 524 passes through the guide countersunk hole 523 one by one and is threadedly connected to the column 511. A spring 525 for elastically supporting the expansion block 521 is sleeved on the guide screw 524. A limit block 526 is fixedly provided at the bottom of the expansion block 521. A limit ring groove 512 is provided on the top surface of the base 51 at the outer periphery of the column 511. The limit blocks 526 are all embedded in the limit ring groove 512 to limit the maximum expansion radius of each expansion block 521.

[0100] The expansion cone 53 is arranged in the expansion support assembly 52 and is located above the column 511. The expansion cone 53 is connected to the column 511 through the expansion screw 54. The outer diameter of the expansion cone 53 gradually decreases from top to bottom to match the inner diameter of the expansion support assembly 52.

[0101] In this embodiment, each pair of expansion blocks 521 is in a state of being tightened on the outside of the column 511 under the action of the spring 525. When machining the two end faces of the flame tube inner cylinder 1, first put its skirt 13 downward on the expansion support assembly 52, the expansion blocks 521 support the inner side of the flame tube inner cylinder 1, and the skirt expansion part 522 supports the inner side of the skirt 13. Then use a wrench to turn the expansion screw 54 to drive the expansion cone 53 downward, and the expansion cone 53 squeezes each expansion block 521 to expand the flame tube inner cylinder 1; at this time, the flame tube inner cylinder 1 can be machined by machining equipment to ensure the flatness of the end face. The support mold 5 avoids the problem of deformation caused by end face machining of the flame tube inner cylinder 1, and ensures the molding quality of the flame tube inner cylinder 1.

[0102] In the description of this specification, the terms "connection", "installation", "fixation" and the like should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0103] In the description of this specification, the description of the terms "one embodiment", "some embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0104] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for forming a flame tube inner cylinder without weld seams, characterized in that: The steps include: 1) Cutting and cutting to obtain a circular blank; 2) first stretching, stretching the circular blank through a first stretching die (2) to form a first drawn blank (11), and subjecting the first drawn blank (11) to a solid solution heat treatment; the first drawn blank (11) is a cylindrical shape with a closed top and an open bottom, the top edge of the first drawn blank (11) is a first round chamfer, the inner diameter of the first drawn blank (11) is larger than the inner cylinder (1) of the flame tube, and the height is smaller than the inner cylinder (1) of the flame tube; 3) a second stretching, wherein the first-drawn blank (11) is stretched by a second stretching die (3) to form a second-drawn blank (12), and the second-drawn blank (12) is subjected to a solid solution heat treatment; the second-drawn blank (12) is a cylindrical shape with a closed top and an open bottom, the inner diameter of the second-drawn blank (12) is equal to the inner cylinder (1) of the flame tube, and the second-drawn blank (12) has the same contour as the skirt (13) of the inner cylinder (1) of the flame tube near the bottom; 4) cutting off the remaining edges, and cutting off the remaining edges at the top and bottom of the second-drawn blank (12) to form the inner cylinder body (1) of the flame tube; 5) roundness calibration, using a calibration die (4) to calibrate the roundness of the inner cylinder (1) of the flame tube; 6) Machining: the inner wall of the flame tube inner cylinder (1) is expanded and supported by a supporting mold (5), and then the top end surface and the bottom end surface of the flame tube inner cylinder (1) are machined.

2. The method for forming the inner cylinder of the flame tube without weld seams according to claim 1, characterized in that: The sum of the radii of the flame tube inner cylinder (1) and the first round chamfer is greater than the radius of the first-drawn blank (11), and the radius of the first round chamfer is 10-15 mm.

3. The method for forming the inner cylinder of the flame tube without weld seams according to claim 1, characterized in that: The first stretching die (2) comprises a first convex die (21), a first pressure ring (22) and a first concave die (23); The first punch (21) is cylindrical, and a first round chamfer is provided at the top edge thereof; the outer diameter of the first punch (21) is larger than the inner diameter of the flame tube inner cylinder (1); The inner diameter of the first pressure ring (22) is clearance-matched with the outer diameter of the first punch (21); The first concave die (23) is provided with a first forming hole (24), and the bottom end of the first forming hole (24) is provided with a second round chamfer.

4. The method for forming the inner cylinder of the flame tube without weld seams according to claim 1, characterized in that: Before the first-stretched blank (11) is stretched for the second time, an air-eliminating hole (14) is provided on the top end surface thereof.

5. The method for forming the inner cylinder of a flame tube without weld seams according to claim 1, characterized in that: The second stretching die (3) comprises a second male die (31), a stripping ring (32), a second blank holder ring (33) and a second female die (34); The second punch (31) is cylindrical, and a third round chamfer is provided on the top edge thereof; the outer diameter of the second punch (31) is equal to the inner diameter of the flame tube inner cylinder (1); The stripping ring (32) is detachably sleeved on the bottom end of the second male mold (31); The inner diameter of the second pressure ring (33) is loosely matched with the outer diameter of the second punch (31), and the outer diameter is equal to the inner diameter of the first drawn blank (11) ±0.5 mm. The outer diameter of the top of the second pressure ring (33) gradually decreases from bottom to top to form a skirt inner molding surface (35); The second concave mold (34) is provided with a second molding hole (36), and the inner diameter of the bottom end of the second molding hole (36) gradually increases from top to bottom to form a skirt outer molding surface (37).

6. The method for forming the inner cylinder of a flame tube without weld seams according to claim 1, characterized in that: The shaping mold (4) comprises a third concave mold (41), a shaping component (42) and a shaping cone (43); The third die (41) is provided with a shaping hole (411) in the vertical direction, the inner diameter of the shaping hole (411) is the same as the outer diameter of the inner cylinder (1) of the flame tube, and the inner diameter of the top end of the shaping hole (411) gradually increases from top to bottom to form a skirt outer shaping portion (412); The shaping component (42) is annular, its inner diameter gradually decreases from top to bottom, its outer diameter is the same as the inner diameter of the flame tube inner cylinder (1), and its top outer diameter gradually increases from bottom to top to form a skirt inner shaping portion (423), the shaping component (42) is composed of a plurality of shaping blocks (421) uniformly distributed along the circumferential direction and wedge blocks (4) respectively arranged between adjacent shaping blocks (421), and the cross section of the shaping block (421) is fan-shaped; The outer diameter of the lower part of the correction cone (43) matches the inner diameter of the correction component (42) and gradually decreases from top to bottom.

7. The method for forming the inner cylinder of a flame tube without weld seams according to claim 1, characterized in that: The supporting mold (5) comprises a base (51), an expansion support assembly (52) and an expansion cone (53); A column (511) is fixedly arranged on the top of the base (51); The expansion support assembly (52) is arranged on the top surface of the base (51) and is located on the outer periphery of the column (511). The inner diameter of the portion above the column (51) gradually decreases from top to bottom, and the outer diameter is the same as the inner diameter of the inner cylinder (1) of the flame tube. The outer diameter of the expansion support assembly (52) near the bottom gradually increases from bottom to top to form a skirt expansion portion (522). The expansion support assembly (52) includes a plurality of expansion blocks (521) uniformly distributed on the outer periphery of the column (511). The cross section of the expansion block (521) is fan-shaped. The expansion block (521) is respectively opened along the radial direction of the column (511). A guide countersunk hole (523) is provided, and a guide screw (524) passes through the guide countersunk hole (523) one by one and is threadedly connected to the column (511); a spring (525) is sleeved on the guide screw (524) for elastically supporting the expansion block (521); a limiting block (526) is fixedly provided at the bottom of the expansion block (521); a limiting ring groove (512) is provided on the top surface of the base (51) located on the outer periphery of the column (511); the limiting blocks (526) are all embedded in the limiting ring groove (512) for limiting the maximum expansion radius of each expansion block (521); The expansion cone (53) is arranged in the expansion support assembly (52) and is located above the column (511). The expansion cone (53) is connected to the column (511) through a expansion screw (54). The outer diameter of the expansion cone (53) gradually decreases from top to bottom to match the inner diameter of the expansion support assembly (52).

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