Metal shell stretching device and stretching method

Abstract

The present application relates to the technical field of metal stretch forming, in particular to a metal steel shell stretching processing device and a stretching method, comprising a steel shell stretching hydraulic machine, a sliding rod is movably arranged on the inner side of the steel shell stretching hydraulic machine, and a shell clamping arm claw is movably arranged on the inner side of the sliding rod. The steel shell multistage stretching mechanism is adopted to realize multiple stretching forming of the processed part and multistage thinning deformation; the structural optimization design of the upper die unit and the lower die unit is utilized to make the nickel layer stress concentrate when the steel shell is thinned and formed; the outer punch assembly is combined with the inner punch assembly, which not only satisfies the buffering effect during downward stretching, but also satisfies the stability during the stripping of the formed steel shell; the steel shell abutting assembly is combined with the pre-injection air to lift and strip the steel shell after air injection between the steel shell and the inner convex core, which realizes soft stripping, avoids the damage of the steel shell during stripping, and reduces the cracking or peeling of the nickel layer caused by mechanical scratching.

Description

Technical Field

[0001] This invention relates to the field of metal stretching and forming technology, specifically to a metal steel shell stretching processing device and stretching method. Background Technology

[0002] In the stretching process of pre-plated nickel steel shells, hydraulic presses are currently widely used equipment. Their core principle is to drive the mold through a hydraulic transmission system to stretch and deform the material. Due to unreasonable design of the die entry angle and die gap, the contact angle between the die and the steel shell surface and the amount of thinning are uneven, which in turn causes stress concentration in the nickel layer and cracks.

[0003] In existing technologies, such as the multi-station, multi-pass stretching hydraulic press and its processing method disclosed in CN102441599A, the workpiece is sequentially transferred from the first station to the last station through controller control, automatically completing the multi-pass continuous stretching process from sheet metal to stretching and forming. It has advantages such as simple and compact structure, small footprint, high degree of automation, low labor intensity for workers, safe and reliable operation, and high production efficiency.

[0004] The above document describes how the workpiece is thinned and deformed sequentially through multiple workstations. However, in actual use, if the formed steel shell is directly lifted by the outer punch, the bottom edge of the steel shell is pushed during the lifting process, causing the steel shell to peel directly from the outer wall of the punch. This can easily damage the nickel layer and may cause the steel shell to wrinkle, thus reducing the yield of the metal steel shell.

[0005] Therefore, this invention proposes a metal steel shell stretching processing device and stretching method to solve the problems of uneven wall thickness reduction in a single stretching process between the existing mold and the steel shell surface, which leads to stress concentration in the nickel layer, cracking, and damage to the nickel layer due to direct peeling during stripping. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a metal steel shell stretching processing device and stretching method to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a metal shell stretching processing device, comprising a steel shell stretching hydraulic press, wherein a slide rod is movably installed on the inner side of the steel shell stretching hydraulic press, and a shell clamping arm is movably installed on the inner side of the slide rod for loading and unloading metal shells for stretching and forming; the inner side of the steel shell stretching hydraulic press is provided with a multi-stage steel shell stretching mechanism, the multi-stage steel shell stretching mechanism comprising an upper die unit and a lower die unit; the upper die unit is composed of a hydraulic component, a lifting seat and a concave die component; the lower die unit is composed of an outer punch component and an inner punch component; the inner punch component includes an inner punch core; a stabilizing stripping mechanism is provided on the inner side of the inner punch core; the stabilizing stripping mechanism includes an air injection component and a steel shell abutment component.

[0008] Preferably, the die assembly includes an upper die annular base and an annular die. The upper surface of the upper die annular base is fixedly connected to one end of a guide post, and the outer surface of the other end of the guide post is slidably connected to the inner wall of the lifting seat. The annular die is fixedly installed on the lower surface of the upper die annular base by bolts, and the lower inner ring surface of the annular die is provided with an appropriate concave angle.

[0009] Preferably, the inner ring surface of the upper mold annular base has a limiting flare, the inner side of which is movably connected to a die core, and the outer ring surface of the die core is fixedly installed with a limiting flange. The outer ring surface of the limiting flange is movably engaged with the inner wall of the limiting flare. The upper end of the die core is fixedly connected to a telescopic sleeve assembly and a telescopic spring. The telescopic sleeve assembly consists of a cylindrical sleeve and a cylindrical rod. The cylindrical sleeve is fixedly installed inside the lifting seat, the upper outer surface of the cylindrical rod is slidably connected to the inner wall of the cylindrical sleeve, and the end of the telescopic spring away from the die core is fixedly connected to the bottom outer surface of the limiting sleeve.

[0010] Preferably, the outer punch assembly includes a lower die annular base and an outer punch sleeve. A telescopic sleeve is fixedly connected to the lower surface of the lower die annular base. The upper surface of the lower die annular base is fixedly connected to the bottom end of the outer punch sleeve. An adaptive slope is provided on the outer surface of the end of the outer punch sleeve away from the lower die annular base. The outer surface of the adaptive slope is adapted to the inner wall of the adaptive concave angle.

[0011] Preferably, the inner punch assembly includes an inner punch core, the outer surface of which is slidably connected to the inner ring sidewall of the outer punch sleeve, a central boss is fixedly installed on the central inner wall of the inner punch core, and an annular cavity is provided between the outer ring surface of the central boss and the inner ring surface of the inner punch core.

[0012] Preferably, the steel shell abutment assembly is integrally formed from a circular sealing plate and a central rod. The end of the central rod away from the circular sealing plate is threadedly connected to a threaded plate. A reserved groove is provided on the inner wall of the bottom end of the inner convex core. The inner surface of the reserved groove is in movable contact with the outer surface of the threaded plate.

[0013] Preferably, a spring thread is slidably sleeved on the upper outer surface of the central rod, one end of the spring thread is fixedly connected to the lower surface of the circular sealing plate, and the other end of the spring thread is fixedly connected to the upper outer surface of the central boss.

[0014] Preferably, the gas injection assembly includes a nitrogen supply chamber seat and a gas injection pipe. The lower surface of the nitrogen supply chamber seat is fixedly connected to the inner surface of the steel shell stretching hydraulic press, and a gas injection hose is sealed to the bottom end of the nitrogen supply chamber seat. An air pump is provided at the input end of the gas injection hose. The input end of the gas injection pipe is connected through the upper surface of the nitrogen supply chamber seat, and the end of the gas injection pipe away from the nitrogen supply chamber seat extends into the interior of the annular cavity.

[0015] Preferably, the inner wall of the circular sealing plate is provided with an annular groove, and an overpressure compensation component is movably installed on the inner side of the annular groove. The overpressure compensation component includes an annular insert and a spring wire. The spring wire is fixedly installed on the top surface of the inner cavity of the annular groove, and the other end of the spring wire is fixedly connected to the inner surface of the annular insert. The cross-section of the annular insert is T-shaped. The inner wall of the central rod is provided with an air intake slot and a central jet slot. The input end of the air intake slot is interconnected with the inner wall of the annular groove, and the output end of the air intake slot is interconnected with the lower inner wall of the central jet slot.

[0016] A stretching method for a metal shell stretching processing device includes the following steps: Step 1: Install and adjust the mold parameters, preheat the hydraulic press and mold to ensure uniform temperature, and apply lubricant to the mold surface and the contact surface of the round steel shell. Step 2: The round steel shell is stretched at a low speed at the first stretching station so that the steel shell gradually enters the die and forms a preliminary shape. The steel shell formed in one step is clamped by the clamping arm and sent to the second stretching station. The steel shell at the second stretching station is then clamped to the third stretching station so that the steel shell is thinned and deformed after multiple stretching. Step 3: After rough machining at the first stretching station, the metal shell is fitted onto the inner punch assembly. The upper die unit of the steel shell stretching hydraulic press is pressed down, causing the outer punch assembly to be pressed down. The die assembly matches the inner punch assembly to form a steel pipe. Step 4: After stretching, maintain pressure for a period of time to shape the steel shell. Then, slowly release the pressure and allow it to cool. The steel shell contact component and the air injection component are combined to inject air between the steel shell and the inner punch component. Then, lift and remove the material to achieve gentle removal.

[0017] Compared with the prior art, the beneficial effects of the present invention are: This invention proposes a metal steel shell stretching processing device and method. It achieves multi-stage stretching and forming of the workpiece through a multi-stage steel shell stretching mechanism, realizing multi-stage thinning deformation. Optimized structural design of the upper and lower die units concentrates nickel layer stress during thinning. The combination of the outer and inner punch assemblies provides both a buffering effect during downward stretching and stability during steel shell stripping. A combination of steel shell contact assembly lifting and pre-air injection injects air between the steel shell and the inner punch core before lifting and stripping, achieving gentle stripping and preventing damage to the steel shell during stripping, thus reducing cracking or peeling of the nickel layer due to mechanical scratching. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the three-dimensional structure of the present invention. Figure 1 ; Figure 2 This is a schematic diagram of the three-dimensional structure of the present invention. Figure 2 ; Figure 3 This is a partial three-dimensional structural diagram of the multi-stage tensioning mechanism for steel shells of the present invention; Figure 4 For the present invention Figure 3 A schematic diagram of the cross-sectional structure at point aa; Figure 5 For the present invention Figure 4 A magnified structural diagram at point A; Figure 6 For the present invention Figure 3 A schematic diagram of the cross-sectional structure at point bb; Figure 7 For the present invention Figure 6 A magnified structural diagram at point B; Figure 8 For the present invention Figure 7 Enlarged structural diagram at point B1; Figure 9 For the present invention Figure 7 Enlarged structural diagram at point B2; Figure 10 This is a schematic diagram of the upper mold annular base in the unpressed state of the present invention; Figure 11 For the present invention Figure 10 A schematic diagram of the cross-sectional structure at the cc point; Figure 12 This is a schematic diagram of the cross-sectional structure at the cc point after the steel shell of the present invention has been formed and lifted. Figure 13 This is a schematic diagram of the connection structure between the inner convex core and the gas injection assembly of the present invention; Figure 14 For the present invention Figure 13 A schematic diagram of the exploded structure; Figure 15 This is a schematic diagram of the disassembled structure of the steel shell abutment component and the support component of the present invention; Figure 16 This is a bottom view of the disassembled structure of the steel shell contact assembly of the present invention.

[0019] In the diagram: 1. Steel shell stretching hydraulic press; 11. Slide rod; 111. Clamping arm; 2. Upper die unit; 21. Hydraulic assembly; 22. Lifting seat; 23. Upper die annular base; 230. Limiting flare; 231. Guide post; 232. Annular die cavity; 2320. Adaptive concave angle; 24. Die cavity core; 240. Limiting flange; 241. Telescopic sleeve assembly one; 242. Telescopic spring; 3. Lower die unit; 31. Lower die annular base; 311. Outer punch sleeve; 3111. Adaptive... 32. Slope angle; 32. Nitrogen supply chamber seat; 321. Gas injection pipe; 33. Inner convex core; 330. Annular cavity; 331. Central boss; 34. Steel shell contact assembly; 341. Circular sealing plate; 342. Central rod; 343. Threaded plate; 3300. Reserved groove; 344. Socketed spring wire; 3410. Annular groove; 34101. Annular insert; 34102. Spring wire; 34100. Air inlet slot; 341000. Central jet slot; 35. Annular cooling plate. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the present invention clear and complete, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only some, not all, embodiments of the present invention, and are merely illustrative of the embodiments of the present invention. They are not intended to limit the embodiments of the present invention. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1, please refer to Figure 1-16This invention provides a technical solution: a metal shell stretching processing device, including a steel shell stretching hydraulic press 1. A slide rod 11 is movably installed inside the steel shell stretching hydraulic press 1, and a shell clamping arm 111 is movably installed inside the slide rod 11 for loading and unloading the metal shell during stretching. A multi-stage steel shell stretching mechanism is provided inside the steel shell stretching hydraulic press 1, including an upper die unit 2 and a lower die unit 3. The upper die unit 2 consists of a hydraulic assembly 21, a lifting seat 22, and a die assembly. The hydraulic assembly 21 is fixedly installed at the top of the steel shell stretching hydraulic press 1, and the output end of the hydraulic assembly 21... The upper surface of the lifting seat 22 is fixedly connected to the upper surface of the lifting seat 22. Guide rods are fixedly installed on the inner walls of the lifting seat 22. The upper outer surface of the guide rods is slidably connected to the inner top surface of the steel shell stretching hydraulic press 1. The die assembly includes an upper die annular base 23 and an annular die 232. The upper surface of the upper die annular base 23 is fixedly connected to one end of the guide post 231, and the outer surface of the other end of the guide post 231 is slidably connected to the inner wall of the lifting seat 22. The annular die 232 is fixedly installed on the lower surface of the upper die annular base 23 by bolts. The lower inner ring surface of the annular die 232 is provided with a matching concave angle 2320. A limiting flare 230 is formed on the inner ring surface of the mold base 23. A die core 24 is movably connected to the inner side of the limiting flare 230. A limiting flange 240 is fixedly installed on the outer ring surface of the die core 24. The outer ring surface of the limiting flange 240 is movably engaged with the inner wall of the limiting flare 230. A telescopic sleeve 241 and a telescopic spring 242 are fixedly connected to the upper end of the die core 24. The telescopic sleeve 241 consists of a cylindrical sleeve and a cylindrical rod. The cylindrical sleeve is fixedly installed inside the lifting seat 22. The upper outer surface of the cylindrical rod is slidably connected to the inner wall of the cylindrical sleeve, and the telescopic spring 242 is away from the die core. One end of 24 is fixedly connected to the outer surface of the bottom end of the limiting sleeve; the lower mold unit 3 is composed of an outer punch assembly and an inner punch assembly. The inner punch assembly includes an inner punch core 33; the outer punch assembly includes a lower mold annular base 31 and an outer punch sleeve 311. A telescopic sleeve assembly 2 is fixedly connected to the lower side surface of the lower mold annular base 31, and the upper side surface of the lower mold annular base 31 is fixedly connected to the bottom end of the outer punch sleeve 311; the outer surface of the outer punch sleeve 311 away from the lower mold annular base 31 is provided with an adapting slope angle 3111, and the outer surface of the adapting slope angle 3111 is adapted to the inner wall of the adapting concave angle 2320. When forming a set of metal shells, firstly, a circular steel sheet coated with lubricant is stably placed at the first stretching station. The hydraulic pressure is appropriately set, and the circular steel shell is stretched at a low speed at the first stretching station, gradually entering the die cavity to form a preliminary shape. The steel shell formed in one step is then clamped by the clamping arm 111 and sent to the second stretching station. The steel shell at the second stretching station is then clamped and sent to the third stretching station, where the steel shell undergoes multiple stretching processes to achieve thinning deformation. For details regarding the second and third stretching stations, please refer to [the relevant documentation]. Figures 3-7As shown, when the upper die annular base 23 and annular die 232 are pressed down at low speed by the hydraulic component 21, the outer die sleeve 311, which was originally fitted outside the inner convex core 33, moves down under pressure. It should be noted that there is a certain gap between the inner ring surface of the upper die annular base 23 and annular die 232 and the outer ring surface of the inner convex core 33, and this gap is the thin wall thickness of the steel shell forming. When the die component and the outer die component are matched, the matching concave angle 2320 and the matching slope angle 3111 are matched to ensure the accuracy of the mold entry angle. During the gradual pressing down of the die component, the steel shell achieves thinning and stretching deformation until the bottom end of the lower die annular base 31 contacts the upper surface of the steel shell stretching hydraulic press 1. After stretching, the pressure is maintained for a period of time to shape the steel shell, and then the pressure is slowly released and cooled.

[0022] Example 2, see attached document Figure 1-16 Based on Example 1, in order to achieve buffer protection during the stretching and forming of the steel shell: A stabilizing unloading mechanism is provided on the inner side of the inner convex core 33. The stabilizing unloading mechanism includes an air injection component and a steel shell contact component 34. The steel shell contact component 34 is integrally formed by a circular sealing plate 341 and a central rod 342. The end of the central rod 342 away from the circular sealing plate 341 is threadedly connected to a threaded plate 343. A reserved groove 3300 is provided on the inner wall of the bottom end of the inner convex core 33. The inner surface of the reserved groove 3300 is in movable contact with the outer surface of the threaded plate 343. A sleeve spring wire 344 is slidably sleeved on the upper outer surface of the central rod 342. One end of the sleeve spring wire 344 is fixedly connected to the lower surface of the circular sealing plate 341, and the other end of the sleeve spring wire 344 is fixedly connected to the upper outer surface of the central boss 331. Reference Figures 10-11 As shown, the steel shell abutment component 34 is in an unaffected state. The circular sealing plate 341 protrudes slightly from the highest position of the inner core 33 under the elastic force of the sleeve spring wire 344. When the steel shell is hydraulically formed, the bottom end of the die core 24 abuts against the top of the steel shell abutment component 34. Then, the entire steel shell abutment component 34 is pressed down. At this time, the sleeve spring wire 344 is compressed and deformed under the action of external pressure, which can play a certain degree of buffering role. By setting a buffer structure in the mold, the impact force during the stretching process is absorbed, and the damage to the nickel layer caused by the impact is reduced. It is worth noting that when the annular die 232 reaches the final position, the bottom of the die core 24 positions and abuts against the top of the steel shell. When the annular die 232 is raised, the limiting flare 230 opened on the inner ring side wall of the upper die annular base 23 matches the limiting protrusion 240, thereby driving the die core 24 to rise and releasing the pressure on the top of the formed steel shell.

[0023] Example 3, refer to Appendix Figure 1-16Based on Example 2, in order to achieve flexible unloading after the steel shell is thinned and formed, and to avoid cracking or peeling of the nickel layer due to mechanical scratching: The gas injection assembly includes a nitrogen supply chamber seat 32 and a gas injection pipe 321. The lower surface of the nitrogen supply chamber seat 32 is fixedly connected to the inner surface of the steel shell stretching hydraulic press 1, and a gas injection hose is sealed to the bottom end of the nitrogen supply chamber seat 32. An air pump is installed at the input end of the gas injection hose. The input end of the gas injection pipe 321 is connected to the upper surface of the nitrogen supply chamber seat 32, and the end of the gas injection pipe 321 away from the nitrogen supply chamber seat 32 extends into the interior of the annular cavity 330. An annular groove 3410 is formed on the inner wall of the circular sealing plate 341. An overpressure compensation assembly is movably installed inside the annular groove 3410. It includes an annular panel 34101 and a spring wire 34102. The spring wire 34102 is fixedly installed on the top surface of the inner cavity of the annular groove 3410. The other end of the spring wire 34102 is fixedly connected to the inner surface of the annular panel 34101. The cross-section of the annular panel 34101 is T-shaped. The inner wall of the central rod 342 is provided with an air inlet slot 34100 and a central jet slot 341000. The input end of the air inlet slot 34100 is connected to the inner wall of the annular groove 34100. The output end of the air inlet slot 34100 is connected to the lower inner wall of the central jet slot 341000. By reference Figures 4-9 and Figures 13-16As shown, when stripping the thinned steel shell, the hydraulic component 21 first moves the die assembly formed by the upper die annular base 23 and the annular die 232 upwards. At this time, the die core 24 is also released from the restriction on the top of the steel shell. Then, by opening the external air pump, nitrogen or argon or other inert gases are added to the nitrogen supply chamber 32 and injected into the annular cavity 330 through the gas injection pipe 321. As the injection pressure increases, the annular insert 34101 inside the annular groove 3410 moves towards the annular cavity 330. When the spring wire 34102 moves inward, it compresses. When the annular panel 34101 moves inward, the channel between the air intake slot 34100 and the annular slot 3410 opens, allowing compressed gas to flow through the air intake slot 34100 and then be ejected outward through the central jet slot 341000. It should be noted that the air intake slots 34100 are arranged in a circular array about the central axis of the central jet slot 341000, and the central jet slot 341000 is located on the steel shell. The central inner wall of the contact assembly 34 has a gradually narrowing structure from bottom to top, and the output end of the central air jet 341000 has a conical flare. The reason for designing the central air jet 341000 as a gradually narrowing structure from bottom to top is to allow the central airflow to be ejected quickly and then enter the space between the top of the circular sealing plate 341 and the inner side of the steel shell through the conical flare structure. After the gas is injected between the two, they are no longer tightly attached. At this time, the steel shell contact assembly 34 is lifted upward by the combined action of the gas lifting and the reverse elastic force of the sleeve spring wire 344, which helps to separate the steel shell from the outer wall of the inner convex core 33. Then, the outer punch sleeve 311 is controlled to rise and reset at a low speed, so that the thinned steel shell can be completely removed, avoiding cracking or peeling of the nickel layer due to mechanical scratching. It should also be noted that the central air jet 341000 can also serve as an auxiliary chip removal structure to prevent the accumulation of steel chips on the surface of the circular sealing plate 341.

[0024] Example 4, see attached document Figure 1-16 Based on Embodiment 3, this embodiment adds a support component: The inner cavity of the annular cavity 330 is provided with a support assembly, which includes an annular cooling plate 35. The outer ring surface of the annular cooling plate 35 is adapted to fit and embedded with the inner ring sidewall of the annular cavity 330. The top outer surface of the annular cooling plate 35 is in movable contact with the lower surface of the circular sealing plate 341. Graphite cores are uniformly embedded in the inner ring surface of the annular cooling plate 35. The annular cooling plate 35, installed within the annular cavity 330, serves to strengthen the overall structural strength of the inner convex core 33 and also acts as a support for the steel shell contact assembly 34. It provides stable support to the bottom side of the circular sealing plate 341, reducing piston sway, ensuring uniform distribution of lifting force, and limiting the downward movement of the steel shell contact assembly 34. This prevents the steel shell contact assembly 34 from being pressed down by the concave mold core 24, causing the center of the steel shell to cave in. Furthermore, the annular cooling plate 35 has a uniformly embedded graphite core on its inner ring surface, allowing the steel shell to transfer heat generated by hydraulic pressure, achieving rapid cooling and hardening before unloading. This uniform cooling reduces internal thermal stress in the steel shell, preventing deformation or cracking after unloading due to stress release. Additionally, the annular cooling plate 35 and the steel shell contact assembly 34 can be quickly disassembled from the inner convex core 33 for easy cleaning or replacement. When assembling the steel shell abutment assembly 34 and the annular cooling plate 35 with the inner convex core 33, the annular cooling plate 35 is first embedded into the annular cavity 330, and then the steel shell abutment assembly 34 is inserted through the center of the annular cooling plate 35. Subsequently, the threaded plate 343 is threadedly matched with the bottom end of the central rod 342, thus achieving rapid installation.

[0025] Example 5, see attached document Figure 1-16 Based on Embodiment 4, the present invention also provides a stretching method for a metal shell stretching processing device, comprising the following steps: Step 1: Install and adjust the mold parameters, preheat the hydraulic press and mold to ensure uniform temperature, and apply lubricant to the mold surface and the contact surface of the round steel shell. Step 2: The round steel shell is stretched at a low speed at the first stretching station so that the steel shell gradually enters the die and forms a preliminary shape. The steel shell formed in one step is clamped and sent to the second stretching station by the clamping arm 111. The steel shell at the second stretching station is then clamped and sent to the third stretching station so that the steel shell is thinned and deformed after multiple stretching. Step 3: After rough processing at the first stretching station, the metal shell is fitted onto the inner punch assembly. The upper die unit 2 of the steel shell stretching hydraulic press 1 is pressed down, causing the outer punch assembly to be pressed down. The die assembly matches the inner punch assembly to form a steel pipe. Step 4: After stretching, maintain pressure for a period of time to shape the steel shell. Then, slowly release the pressure and cool it. The steel shell contact component 34 is combined with the air injection component to inject air between the steel shell and the inner punch component. Then, lift and strip the material to achieve gentle stripping.

[0026] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A metal shell stretching processing device, comprising a steel shell stretching hydraulic press (1), wherein a slide rod (11) is movably installed on the inner side of the steel shell stretching hydraulic press (1), and a shell clamping arm (111) is movably installed on the inner side of the slide rod (11) for loading and unloading metal shells for stretching and forming, characterized in that: The inner side of the steel shell stretching hydraulic press (1) is provided with a multi-stage steel shell stretching mechanism. The multi-stage steel shell stretching mechanism includes an upper die unit (2) and a lower die unit (3). The upper die unit (2) is composed of a hydraulic component (21), a lifting seat (22) and a die cavity component. The lower die unit (3) is composed of an outer punch component and an inner punch component. The inner punch component includes an inner punch core (33). The inner punch core (33) is provided with a stabilizing stripping mechanism. The stabilizing stripping mechanism includes an air injection component and a steel shell contact component (34). The steel shell abutment assembly (34) is integrally formed from a circular sealing plate (341) and a central rod (342). The end of the central rod (342) away from the circular sealing plate (341) is threadedly connected to a threaded plate (343). A reserved groove (3300) is provided on the inner wall of the bottom end of the inner convex core (33). The inner surface of the reserved groove (3300) is in movable contact with the outer surface of the threaded plate (343). An annular groove (3410) is provided on the inner wall of the circular sealing plate (341). An overpressure compensation assembly is movably installed on the inner side of the annular groove (3410). The overpressure compensation assembly includes an annular insert (34101) and a spring wire (3). 4102), the spring wire (34102) is fixedly installed on the top surface of the inner cavity of the annular groove (3410), the other end of the spring wire (34102) is fixedly connected to the inner surface of the annular panel (34101), and the cross section of the annular panel (34101) is a "T" shaped structure. The inner wall of the central rod (342) is provided with an air intake slot (34100) and a central jet slot (341000). The input end of the air intake slot (34100) is connected to the inner wall of the annular groove (3410), and the output end of the air intake slot (34100) is connected to the lower inner wall of the central jet slot (341000).

2. The metal steel shell stretching processing device according to claim 1, characterized in that: The die assembly includes an upper die annular base (23) and an annular die (232). The upper surface of the upper die annular base (23) is fixedly connected to one end of the guide post (231), and the outer surface of the other end of the guide post (231) is slidably connected to the inner wall of the lifting seat (22). The annular die (232) is fixedly installed on the lower surface of the upper die annular base (23) by bolts. The lower inner ring surface of the annular die (232) is provided with a matching concave angle (2320).

3. The metal steel shell stretching processing device according to claim 2, characterized in that: The inner ring surface of the upper mold annular base (23) is provided with a limiting flare (230). The inner side of the limiting flare (230) is movably connected to the die core (24). The outer ring surface of the die core (24) is fixedly installed with a limiting flange (240). The outer ring surface of the limiting flange (240) is movably engaged with the inner wall of the limiting flare (230). The upper end of the die core (24) is fixedly connected with a telescopic sleeve group one (241) and a telescopic spring (242). The telescopic sleeve group one (241) is composed of a cylindrical sleeve and a cylindrical rod. The cylindrical sleeve is fixedly installed inside the lifting seat (22). The upper outer surface of the cylindrical rod is slidably connected to the inner wall of the cylindrical sleeve. The end of the telescopic spring (242) away from the die core (24) is fixedly connected to the bottom outer surface of the limiting sleeve.

4. The metal steel shell stretching processing device according to claim 2, characterized in that: The outer punch assembly includes a lower die annular base (31) and an outer punch sleeve (311). A telescopic sleeve is fixedly connected to the lower surface of the lower die annular base (31). The upper surface of the lower die annular base (31) is fixedly connected to the bottom end of the outer punch sleeve (311). An adaptive slope angle (3111) is provided on the outer surface of the end of the outer punch sleeve (311) away from the lower die annular base (31). The outer surface of the adaptive slope angle (3111) is adapted to the inner wall of the adaptive concave angle (2320).

5. The metal steel shell stretching processing device according to claim 4, characterized in that: The inner punch assembly includes an inner punch core (33), the outer surface of which is slidably connected to the inner ring sidewall of the outer punch sleeve (311), and a central boss (331) is fixedly installed on the central inner wall of the inner punch core (33). An annular cavity (330) is provided between the outer ring surface of the central boss (331) and the inner ring surface of the inner punch core (33).

6. The metal steel shell stretching processing device according to claim 1, characterized in that: The upper outer surface of the central rod (342) is slidably fitted with a sleeve spring wire (344). One end of the sleeve spring wire (344) is fixedly connected to the lower surface of the circular sealing plate (341), and the other end of the sleeve spring wire (344) is fixedly connected to the upper outer surface of the central boss (331).

7. The metal steel shell stretching processing device according to claim 1, characterized in that: The gas injection assembly includes a nitrogen supply chamber seat (32) and a gas injection pipe (321). The lower surface of the nitrogen supply chamber seat (32) is fixedly connected to the inner surface of the steel shell stretching hydraulic press (1), and the bottom end of the nitrogen supply chamber seat (32) is sealed with a gas injection hose. An air pump is provided at the input end of the gas injection hose. The input end of the gas injection pipe (321) is connected through to the upper surface of the nitrogen supply chamber seat (32), and the end of the gas injection pipe (321) away from the nitrogen supply chamber seat (32) extends into the interior of the annular cavity (330).

8. A stretching method for a metal shell stretching processing apparatus, implemented based on the metal shell stretching processing apparatus according to any one of claims 1-7, characterized in that: The stretching method of this metal shell stretching processing device includes the following steps: Step 1: Install and adjust the mold parameters, preheat the hydraulic press and mold to ensure uniform temperature, and apply lubricant to the mold surface and the contact surface of the round steel shell. Step 2: The round steel shell is stretched at a low speed at the first stretching station so that the steel shell gradually enters the die and forms a preliminary shape. The steel shell formed in one step is clamped and sent to the second stretching station by the clamping arm claw (111). The steel shell at the second stretching station is then clamped and sent to the third stretching station so that the steel shell is thinned and deformed after multiple stretching steps. Step 3: The metal shell after rough processing at the first stretching station is fitted onto the inner punch assembly. The upper die unit (2) of the steel shell stretching hydraulic press (1) is pressed down, causing the outer punch assembly to be pressed down. The concave die assembly matches the inner punch assembly to form a steel pipe. Step 4: After stretching, maintain pressure for a period of time to shape the steel shell. Then slowly release the pressure and cool it. The steel shell contact component (34) is combined with the air injection component to inject air between the steel shell and the inner punch component. Then lift and remove the material to achieve gentle removal.

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