Steel pipe bulging device and bulging method

Abstract

The present invention discloses a steel pipe bulging device and a bulging method, comprising a bulging die formed by closing an upper die and a lower die, and a bulging mechanism; a fixed die cavity for accommodating the middle part of the steel pipe, a first accommodating space located at the first end side of the fixed die cavity, and a second accommodating space located at the second end side of the fixed die cavity are formed in the bulging die, and a movable entry block assembly is provided in the first accommodating space and the second accommodating space, and a bulging die cavity for accommodating the corresponding end part of the steel pipe is formed on the movable entry block assembly; the bulging mechanism comprises a first blocking mechanism arranged at the first end side of the bulging die, a second blocking mechanism formed at the second end side of the bulging die, and an injection channel for injecting high-pressure liquid formed on the first blocking mechanism and / or the second blocking mechanism; the first blocking mechanism and the second blocking mechanism both comprise a movable push block arranged on the outside of the corresponding movable block assembly, a sealing punch arranged on the movable push block, and a driving device connected to the movable push block.

Description

Technical Field

[0001] The present application relates to the technical field of steel pipe forming equipment, and in particular to a steel pipe expansion device and expansion method. Background Art

[0002] Currently, steel pipe expansion is often achieved by using a bulging die in conjunction with high-pressure liquid. When bulging the ends of a steel pipe, a fixed-length die is typically used. After the steel pipe is placed in the die cavity, a sealing punch seals both ends of the pipe. High-pressure liquid is then injected into the pipe, using the liquid pressure to form the pipe. However, if the required elongation for expansion exceeds the elongation of the pipe wall, the pipe will rupture, making it impossible to form the pipe. Summary of the Invention

[0003] In view of the above-mentioned deficiencies in the prior art, the technical problem to be solved by the present application is to provide a bulging device and a bulging method that can reduce the probability of a steel pipe being ruptured.

[0004] In order to solve the above technical problems, the present application provides a steel pipe bulging device, including a bulging mold formed by closing an upper mold and a lower mold and a bulging mechanism; the bulging mold is formed with a fixed mold cavity for accommodating the middle part of the steel pipe, and a movable block assembly located at both ends of the fixed mold cavity, and the movable block assembly is formed with a bulging mold cavity for accommodating the corresponding end parts of the steel pipe; the bulging mechanism includes a first sealing mechanism provided on the first end side of the bulging mold for sealing the first end of the steel pipe, a second sealing mechanism formed on the second end side of the bulging mold for sealing the second end of the steel pipe, and an injection channel formed on the first sealing mechanism and / or the second sealing mechanism and used for injecting high-pressure liquid into the steel pipe, the first sealing mechanism and the second sealing mechanism are respectively used to compress the two movable block assemblies.

[0005] Furthermore, the first sealing mechanism and the second sealing mechanism both include a movable push block arranged on the outside of the corresponding movable entry block assembly, a sealing punch arranged on the movable push block, and a driving device connected to the movable push block, the driving device is used to drive the movable push block to move toward the fixed mold cavity to axially compress the movable entry block assembly, and the movable push block drives the sealing punch to seal the end of the steel pipe.

[0006] Furthermore, the movable push block assembly includes a self-recovering compression assembly arranged in the corresponding accommodating space and a sliding assembly that slides in the corresponding accommodating space and is located outside the compression assembly. The sliding assembly presses the compression assembly inward under the thrust of the movable push block.

[0007] Furthermore, the compression assembly includes a plurality of movable plates that are nested layer by layer from the inside to the outside and a self-recovery component located between each two adjacent movable plates to automatically reset each movable plate; there is a predetermined compression spacing between each two adjacent movable plates when they are not pressed by the sliding assembly, and the compression spacing between each two adjacent movable plates gradually decreases under the pressure of the sliding assembly until the movable plates are stacked against each other.

[0008] Furthermore, the first end side position of the lower mold has a first lower accommodating groove formed by being recessed downwardly, and the second end side position of the lower mold has a second lower accommodating groove formed by being recessed downwardly, the first lower accommodating groove and the second lower accommodating groove respectively penetrate the lower mold in opposite directions, and lower movable insertion blocks are provided in the first lower accommodating groove and the second lower accommodating groove; a first upper accommodating groove that matches the position of the first lower accommodating groove is formed at the lower end surface of the upper mold corresponding to the position of the second lower accommodating groove, and upper movable insertion blocks are provided in the first upper accommodating groove and the second upper accommodating groove;

[0009] The first lower accommodating groove and the first upper accommodating groove form the first accommodating space in the mold closing state, and the second lower accommodating groove and the second upper accommodating groove form the second accommodating space in the mold closing state; the lower movable entry block in the first lower accommodating groove and the upper movable entry block in the first upper accommodating groove form a movable entry block assembly located in the first accommodating space in the mold closing state, and the lower movable entry block in the second lower accommodating groove and the upper movable entry block in the second upper accommodating groove form a movable entry block assembly located in the second accommodating space in the mold closing state.

[0010] Furthermore, a lower fixed cavity is formed on the upper end surface of the lower mold at a position between the first lower accommodating groove and the second lower accommodating groove, and both ends of the lower fixed cavity are respectively connected to the first lower accommodating groove and the second lower accommodating groove; an upper fixed cavity is formed on the lower end surface of the upper mold at a position between the first upper accommodating groove and the second upper accommodating groove, and both ends of the upper fixed cavity are respectively connected to the first upper accommodating groove and the second upper accommodating groove; the lower fixed cavity and the upper fixed cavity form the fixed mold cavity in the mold closing state.

[0011] Furthermore, the lower movable entry block includes a lower sliding block arranged in the corresponding lower accommodating groove and a lower compression part arranged between the lower sliding block and the lower fixed cavity, and the lower sliding block can slide toward the fixed mold cavity and compress the lower compression part; the upper movable entry block includes an upper sliding block arranged in the corresponding upper accommodating groove and an upper compression part arranged between the upper sliding block and the upper fixed cavity, and the upper sliding block can slide toward the fixed mold cavity and compress the upper compression part; the lower sliding block and the upper sliding block form the sliding assembly in the mold closing state, and the lower compression part and the upper compression part form the compression assembly in the mold closing state.

[0012] Furthermore, the lower compression part includes a plurality of lower movable plates located between the lower sliding block and the lower fixed cavity and a first self-recovering element located between each two adjacent lower movable plates, and a lower compression gap is provided between each two adjacent lower movable plates; the upper compression part includes a plurality of upper movable plates located between the upper sliding block and the upper fixed cavity and a second self-recovering element located between each two adjacent upper movable plates, and an upper compression gap is provided between each two adjacent upper movable plates; the upper movable plate and the lower movable plate form the movable plate in the mold closing state, and the first self-recovering element and the second self-recovering element form the self-recovering component in the mold closing state.

[0013] Furthermore, the first self-recovering element is a first return spring, one end of the first return spring is pressed against the lower sliding block, and the other end is pressed against the inner groove wall of the lower accommodating groove after passing through each lower moving plate in sequence, and the lower sliding block is connected to the lower moving plate adjacent to it; the second self-recovering element is a second return spring, one end of the second return spring is pressed against the upper sliding block, and the other end is pressed against the inner groove wall of the upper accommodating groove after passing through each upper moving plate in sequence, and the upper sliding block is connected to the upper moving plate adjacent to it.

[0014] Furthermore, the lower movable plate includes a lower stacking plate, a first nesting groove formed on the inner side of the lower stacking plate, and a first nesting block formed on the outer side of the lower stacking plate, wherein the notch size of the first nesting groove is smaller than the inner size of the groove; the first nesting block has a first inserting head embedded in the first nesting groove and a first connecting portion connected between the first inserting head and the lower stacking plate and movably provided at the notch of the first nesting groove, the thickness of the first inserting head is smaller than the depth of the first nesting groove, and the thickness of the first connecting portion is greater than the depth of the notch of the first nesting groove;

[0015] The upper movable plate includes an upper stacking plate, a second nesting groove formed on the inner side of the upper stacking plate, and a second nesting block formed on the outer side of the upper stacking plate, the slot size of the second nesting groove is smaller than the slot inner size; the second nesting block has a second embedding head embedded in the second nesting groove and a second connecting part connected between the second embedding head and the upper stacking plate and movably passed through the slot of the second nesting groove, the thickness of the second embedding head is smaller than the depth of the second nesting groove, and the thickness of the second connecting part is greater than the depth of the slot of the second nesting groove.

[0016] The lockhole that is formed on the two ends of the hinge part is formed on the upper surface of the second end of the hinge part, and the lockhole that is formed on the upper surface of the second end of the hinge part is formed.

[0017] The upper stacking plate includes a first upper side plate and a second upper side plate located in the same plane and spaced apart from each other, the outer side surfaces of the first upper side plate and the second upper side plate respectively extending outward to form an upper extension plate, the outer ends of the two upper extension plates are connected to an upper connecting plate, the two ends of the upper connecting plate respectively protrude from the outer facades of the two upper extension plates to form two upper convex portions, and the two upper extension plates and the upper connecting plate enclose to form the second nesting groove; the spacing space between the first upper side plate and the second upper side plate forms the notch of the second nesting groove, the inner facades of the two upper extension plates form the two side groove walls of the second nesting groove, the outer facades of the two upper extension plates form the second connecting portion, the inner side surface of the upper connecting plate forms the groove bottom wall of the second nesting groove, and the outer side surface of the upper connecting plate and the two upper convex portions form the second embedding head of the second nesting block.

[0018] The present application also provides a steel pipe bulging method, which utilizes the above-mentioned steel pipe bulging device to bulge the steel pipe, comprising the following steps:

[0019] S1. Close the upper die and the lower die so that the middle of the steel tube to be expanded is located in the fixed die cavity, and both ends of the steel tube to be expanded are located in the two expansion die cavities respectively;

[0020] S2. The driving devices of the first and second sealing mechanisms respectively drive the two movable push blocks to move toward the fixed die cavity, so that the sealing punches of the first and second sealing mechanisms are respectively pushed into the two ends of the steel pipe to seal the two ends of the steel pipe;

[0021] S3. High-pressure liquid is injected into the steel pipe through the injection channel of the first plugging mechanism and / or the second plugging mechanism. At the same time, the two driving devices continue to drive the two movable push blocks to compress the two movable input block assemblies inward, and the two sealing punches respectively compress the two ends of the steel pipe and feed the bulged part of the steel pipe;

[0022] S4. The two driving devices respectively drive the two movable push blocks to reset, so that the two sealing punches are reset along with the two movable push blocks, the two movable input block assemblies are reset, and the upper die and the lower die are separated to take out the bulged steel pipe.

[0023] Due to the adoption of the above technical solution, the technical effects of the present invention are:

[0024] When using the steel tube bulging device of the present invention to bulge a steel tube, after the upper and lower dies are closed, the middle of the steel tube is located within the fixed die cavity, and the ends of the steel tube are respectively located within the two bulging die cavities. A first sealing mechanism and a second sealing mechanism respectively seal the ends of the steel tube, and then high-pressure liquid is injected into the steel tube through the injection pipe to bulge the ends of the steel tube. During the bulging process, the first and second sealing mechanisms respectively compress the two movable block assemblies, and also compress the steel tube, thereby providing a simultaneous material replenishment effect during bulging, thereby reducing the probability of the steel tube rupturing during the bulging process. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0026] Figure 1 It is a top view of a preferred embodiment of a steel tube bulging device of the present invention;

[0027] Figure 2 yes Figure 1 AA cross-sectional view;

[0028] Figure 3 This is a structural diagram of a lower movable entry block in a steel pipe bulging device of the present invention;

[0029] Figure 4 yes Figure 3 Enlarged view of a in the middle;

[0030] Figure 5 This is a structural diagram of an upper movable feed block in a steel pipe bulging device of the present invention;

[0031] Figure 6 yes Figure 5 Enlarged view of middle b;

[0032] Figure 7 This is a structural schematic diagram of a lower movable plate in a steel tube bulging device of the present invention;

[0033] Figure 8 This is a structural schematic diagram of an upper movable plate in a steel tube bulging device of the present invention;

[0034] Figure 9 This is a structural schematic diagram of a lower die in a steel tube bulging device of the present invention;

[0035] Figure 10 This is a structural schematic diagram of an upper die in a steel tube bulging device of the present invention;

[0036] Figure 11 It is a structural diagram of the steel pipe to be expanded;

[0037] Figure 12 It is a schematic diagram of the structure of the steel pipe after bulging.

[0038] Reference numerals in the drawings include:

[0039] 1. Bulging die; 2. First blocking mechanism; 3. Second blocking mechanism; 11. Upper die; 12. Lower die; 13. Fixed die cavity; 14. First accommodating space; 15. Second accommodating space; 4. Movable insert assembly; 41. Bulging die cavity; 21. First movable push block; 22. First sealing punch; 23. Injection channel; 24. First driving device; 31. Second movable push block; 32. Second sealing punch; 33. Second driving device; 141. First lower accommodating groove; 151. Second lower accommodating groove; 142. First upper accommodating groove; 152, second upper accommodating groove; 42, lower movable entry block; 411, lower bulging cavity; 43, upper movable entry block; 412, upper bulging cavity; 131, lower fixed cavity; 132, upper fixed cavity; 421, lower sliding block; 422, lower compression part; 431, upper sliding block; 432, upper compression part; 4221, lower movable plate; 4222, first self-restoring element; 4321, upper movable plate; 4322, second self-restoring element; 42211, lower stacking plate; 42212, first a nesting groove; 42213, a first nesting block; 422131, a first insert; 422132, a first connecting portion; 43211, an upper stacking plate; 43212, a second nesting groove; 43213, a second nesting block; 432131, a second insert; 432132, a second connecting portion; 422111, a first lower side plate; 422112, a second lower side plate; 422113, a lower extension plate; 422114, a lower connecting plate; 432111, a first upper side plate; 432112, a second upper side plate; Plate; 432113, upper extension plate; 432114, upper connecting plate; 4211, third nesting groove; 4311, fourth nesting groove; 121, lower guide groove; 4212, first lower guide protrusion; 42214, second lower guide protrusion; 4213, lower step; 122, lower avoidance groove; 111, upper guide groove; 4312, first upper guide protrusion; 43214, second upper guide protrusion; 4313, upper step; 112, upper avoidance groove; 231, first channel; 232, second channel. DETAILED DESCRIPTION

[0040] To make the purpose, technical solutions, and advantages of this application more clear, the technical solutions of this application will be clearly and completely described below in conjunction with the specific embodiments of this application and the corresponding drawings. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0041] It should be noted that when an element is referred to as being “fixed to” another element, it may be directly on the other element or there may be an intermediate element. When an element is referred to as being “connected to” another element, it may be directly connected to the other element or there may be an intermediate element.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0043] like Figure 1 and Figure 2 As shown, an embodiment of a steel tube bulging device of the present invention includes a bulging die 1 and a bulging mechanism. The bulging die 1 is formed by closing an upper die 11 and a lower die 12. A fixed die cavity 13, a first accommodating space 14, and a second accommodating space 15 are formed in the bulging die 1. The fixed die cavity 13 is used to accommodate the middle part of the steel tube. The first accommodating space 14 is located at the first end side of the fixed die cavity 13, and the second accommodating space 15 is located at the second end side of the fixed die cavity 13. Both ends of the fixed die cavity 13 have movable block assemblies 4, and the two movable block assemblies 4 are respectively located in the first accommodating space 14 and the second accommodating space 15. A bulging die cavity 41 is formed on the movable block assembly 4. The bulging die cavity 41 is used to accommodate the end of the steel tube, and the size of the bulging die cavity is adapted to the size of the end of the steel tube after bulging. The bulging mechanism includes a first sealing mechanism 2 provided on the first end side of the bulging mold 1 for sealing the first end of the steel pipe, a second sealing mechanism 3 formed on the second end side of the bulging mold 1 for sealing the second end of the steel pipe, and an injection channel 5 formed on the first sealing mechanism 2 and / or the second sealing mechanism 3 and used for injecting high-pressure liquid into the steel pipe. The first sealing mechanism 2 and the second sealing mechanism 3 are respectively used to compress the two movable block components.

[0044] A first lower accommodating groove 141 is formed on the lower mold 12, and the first lower accommodating groove 141 is located on the first end side of the lower mold 12. The first lower accommodating groove 141 is formed by the upper end surface of the lower mold 12 being recessed downward. A second lower accommodating groove 151 is also formed on the lower mold 12, and the second lower accommodating groove 151 is located on the second end side of the lower mold 12. The second lower accommodating groove 151 is formed by the upper end surface of the lower mold 12 being recessed downward. The first lower accommodating groove 141 and the second lower accommodating groove 151 respectively penetrate the lower mold 12 in opposite directions (opposite directions). The lower end surface of the upper mold 11 is formed with a first upper accommodating groove 142, which corresponds to the position of the first lower accommodating groove 141 and is adapted to the first lower accommodating groove 141. The lower end surface of the upper mold 11 is formed with a second upper accommodating groove 152, which corresponds to the position of the second lower accommodating groove 151 and is adapted to the second lower accommodating groove 151. When the upper mold 11 and the lower mold 12 are in the mold-clamped state, the first lower accommodating groove 141 and the first upper accommodating groove 142 form the first accommodating space 14, and the second lower accommodating groove 151 and the second upper accommodating groove 152 form the second accommodating space 15.

[0045] A lower movable entry block 42 is provided in each of the first lower accommodating groove 141 and the second lower accommodating groove 151 , and a lower expansion cavity 411 is formed on the lower movable entry block 42 ; an upper movable entry block 43 is provided in each of the first upper accommodating groove 142 and the second upper accommodating groove 152 , and an upper expansion cavity 412 is formed on the upper movable entry block 43 . When the upper mold 11 and the lower mold 12 are in the clamping state, the lower movable entry block 42 in the first lower accommodating groove 141 and the upper movable entry block 43 in the first upper accommodating groove 142 form a movable entry block assembly 4 located in the first accommodating space 14, the lower movable entry block 42 in the second lower accommodating groove 151 and the upper movable entry block 43 in the second upper accommodating groove 152 form a movable entry block assembly 4 located in the second accommodating space 15, the lower bulging cavity 411 on the lower movable entry block 42 in the first accommodating space 14 and the upper bulging cavity 412 on the upper movable entry block 43 form a bulging mold cavity 41, and the lower bulging cavity 411 on the lower movable entry block 42 in the second accommodating space 15 and the upper bulging cavity 412 on the upper movable block also form a bulging mold cavity 41.

[0046] A lower fixed cavity 131 is formed on the upper end surface of the lower mold 12. The lower fixed cavity 131 is located between the first lower accommodating groove 141 and the second lower accommodating groove 151. One end of the lower fixed cavity 131 is connected to the first lower accommodating groove 141, and the other end of the lower fixed cavity 131 is connected to the second lower accommodating groove 151. An upper fixed cavity 132 is formed on the lower end surface of the upper mold 11. The upper fixed cavity 132 is located between the first upper accommodating groove 142 and the second upper accommodating groove 152. One end of the upper fixed cavity 132 is connected to the first upper accommodating groove 142, and the other end of the upper fixed cavity 132 is connected to the second upper accommodating groove 152. When the upper mold 11 and the lower mold 12 are in the mold-clamped state, the lower fixed cavity 131 and the upper fixed cavity 132 form the fixed mold cavity 13.

[0047] The movable block assembly 4 includes a compression assembly and a sliding assembly. The compression assembly is arranged in the corresponding accommodating space, that is, the compression assembly on the movable block assembly 4 located in the first accommodating space 14 is located in the first accommodating space 14, and the compression assembly on the movable block assembly 4 located in the second accommodating space 15 is located in the second accommodating space 15. The compression assembly is in a compressed state and can self-recover after the pressure it is subjected to disappears. The sliding assembly slides and fits in the corresponding accommodating space, that is, the sliding assembly on the movable block assembly 4 located in the first accommodating space 14 slides and fits in the first accommodating space 14, and the sliding assembly on the movable block assembly 4 located in the second accommodating space 15 slides and fits in the second accommodating space 15. The sliding assembly is located on the outside of the compression assembly (the side facing away from the fixed mold cavity 13. In the subsequent description, the side facing away from the fixed mold cavity 13 is the outside, and the opposite is the inside). The sliding assembly can slide inward and press the compression assembly.

[0048] The compression assembly includes a plurality of movable plates and a self-restoring component. The plurality of movable plates are nested layer by layer from the inside to the outside. The self-restoring component is located between each two adjacent movable plates, and the self-restoring component is used to automatically reset each movable plate. When not pressed by the sliding assembly, there is a predetermined first compression spacing between each two adjacent movable plates, and the sum of all first compression spacings is compatible with the size of the material that needs to be supplemented during the steel pipe expansion process. In another embodiment, a second compression spacing is provided between the outermost movable plate and the sliding assembly, and a third compression spacing is provided between the innermost movable plate and the inner side wall of the corresponding accommodating space. The sum of the second compression spacing, the third compression spacing and all first compression spacings is compatible with the size of the material that needs to be supplemented during the steel pipe expansion process. Under the pressure of the sliding assembly, the first compression spacing gradually decreases until the movable plates are stacked against each other. In this way, during the expansion process of the steel pipe ends, the movable plates support the steel pipe ends, and the distributed first compression intervals can divide the distance between the sliding assembly and the fixed mold cavity 13 into several parts, preventing the steel pipe from being ruptured due to the excessive distance between the sliding assembly and the fixed mold cavity 13. As the sliding assembly gradually pushes inward, it pushes the compression assembly inward, causing the axial length of the movable entry block assembly 4 to gradually decrease, ultimately matching the length of the steel pipe end to be expanded, thereby completing the steel pipe expansion.

[0049] like Figure 3 and Figure 5As shown, the lower movable entry block 42 includes a lower sliding block 421 and a lower compression portion 422. The lower sliding block 421 is disposed in the corresponding lower accommodating groove, that is, the lower sliding block 421 on the lower movable entry block 42 located in the first lower accommodating groove 141 is located in the first lower accommodating groove 141, and the lower sliding block 421 on the lower movable entry block 42 located in the second lower accommodating groove 151 is located in the second lower accommodating groove 151. The lower compression portion 422 is disposed between the lower sliding block 421 and the lower fixed cavity 131. The lower sliding block 421 can slide toward the fixed mold cavity 13, that is, the lower sliding block 421 can slide toward the lower fixed cavity 131, and the lower sliding block 421 is used to compress the lower compression portion 422. The upper movable input block 43 includes an upper sliding block 431 and an upper compression portion 432. The upper sliding block 431 is arranged in the corresponding upper accommodating groove, that is, the upper sliding block 431 on the upper movable input block 43 located in the first upper accommodating groove 142 is located in the first upper accommodating groove 142, and the upper sliding block 431 on the upper movable input block 43 located in the second upper accommodating groove 152 is located in the second upper accommodating groove 152. The upper compression portion 432 is arranged between the upper sliding block 431 and the upper fixed cavity 132. The upper sliding block 431 can slide toward the fixed cavity 13, that is, the upper sliding block 431 can slide toward the upper fixed cavity 132, and the upper sliding block 431 is used to compress the upper compression portion 432. When the upper mold 11 and the lower mold 12 are in the mold closing state, the lower sliding block 421 and the upper sliding block 431 form the sliding assembly, and the lower compression portion 422 and the upper compression portion 432 form the compression assembly.

[0050] The lower compression section 422 includes a plurality of lower movable plates 4221 and a first self-restoring element 4222. The plurality of lower movable plates 4221 are located between the lower sliding block 421 and the lower fixed cavity 131. The first self-restoring element 4222 is located between each two adjacent lower movable plates 4221, and each adjacent lower movable plates 4221 have a lower compression gap. The upper compression section 432 includes a plurality of upper movable plates 4321 and a second self-restoring element 4322. The plurality of upper movable plates 4321 are located between the upper sliding block 431 and the upper fixed cavity 132. The second self-restoring element 4322 is located between each two adjacent upper movable plates 4321, and each adjacent upper movable plates 4321 have an upper compression gap. When the upper mold 11 and the lower mold 12 are in the mold closing state, the upper movable plates 4321 and the lower movable plates 4221 form the movable plates, and the first self-restoring element 4222 and the second self-restoring element 4322 form the self-restoring component. The upper sliding block 431 can sequentially push each upper movable plate 4321 toward the fixed mold cavity 13, thereby compressing each upper compression gap, and the lower sliding block 421 can sequentially push each lower movable plate 4221 toward the fixed mold cavity 13, thereby compressing each lower compression gap.

[0051] like Figure 4 As shown, the lower movable plate 4221 includes a lower stacking plate 42211, a first nesting groove 42212 and a first nesting block 42213, the first nesting groove 42212 is formed on the inner side of the lower stacking plate 42211, the first nesting block 42213 is formed on the outer side of the lower stacking plate 42211, and the slot size of the first nesting groove 42212 is smaller than the slot inner size; the first nesting block 42213 has a first embedding head 422131 and a first connecting portion 422132, the first embedding head 422131 is embedded in the first nesting groove 42212, the first connecting portion 422132 is connected between the first embedding head 422131 and the lower stacking plate 42211, and the first connecting portion 422132 is movably arranged at the slot of the first nesting groove 42212. The thickness of the first inserting head 422131 is less than the depth of the first nesting groove 42212, and the thickness of the first connecting portion 422132 is greater than the depth of the notch of the first nesting groove 42212. The nesting action of the first nesting block 42213 and the first nesting groove 42212 allows the outermost lower movable plate 4221 to move outward and reset in sequence while the lower movable plate 4221 moves outward and resets.

[0052] like Figure 6 As shown, the upper movable plate 4321 includes an upper stacking plate 43211, a second nesting groove 43212 and a second nesting block 43213, wherein the second nesting groove 43212 is formed on the inner side of the upper stacking plate 43211, and the second nesting block 43213 is formed on the outer side of the upper stacking plate 43211, and the notch size of the second nesting groove 43212 is smaller than the inner size of the groove; the second nesting block 43213 has a second embedding head 432131 and a second connecting portion 432132, and the second nesting block 43213 has a second embedding head 432131 and a second connecting portion 432132. The second inserting head 432131 is embedded in the second nesting groove 43212. The second connecting portion 432132 is connected between the second inserting head 432131 and the upper stacking plate 43211. The second connecting portion 432132 is movably inserted into the notch of the second nesting groove 43212. The thickness of the second inserting head 432131 is less than the depth of the second nesting groove 43212, while the thickness of the second connecting portion 432132 is greater than the depth of the notch of the second nesting groove 43212. Through the nesting action of the second nesting block 43213 and the second nesting groove 43212, when the outermost upper movable plate 4321 moves outward and resets, it can sequentially drive the other upper movable plates 4321 to move outward and reset.

[0053] like Figure 7As shown, the lower stacking plate 42211 includes a first lower side plate 422111 and a second lower side plate 422112, the first lower side plate 422111 and the second lower side plate 422112 are located in the same plane, the first lower side plate 422111 and the second lower side plate 422112 are spaced apart from each other, the outer side surfaces of the first lower side plate 422111 and the second lower side plate 422112 respectively extend outward to form a lower extension plate 422113, the outer ends of the two lower extension plates 422113 are connected to a lower connecting plate 422114, the two ends of the lower connecting plate 422114 respectively protrude from the outer facades of the two lower extension plates 422113 to form two lower convex portions, the two lower extension plates 422113 and the lower connecting plate 422114 together form the first nesting groove 42212; the interval space between the first lower side plate 422111 and the second lower side plate 422112 forms the notch of the first nesting groove 42212, the inner facades of the two lower extension plates 422113 form the two side groove walls of the first nesting groove 42212, the outer facades of the two lower extension plates 422113 form the first connecting portion 422132, the inner side surface of the lower connecting plate 422114 forms the bottom wall of the first nesting groove 42212, the outer side surface of the lower connecting plate 422114 and the two lower protrusions form the first embedding head 422131 of the first nesting block 42213.

[0054] like Figure 8 As shown, the upper stacking plate 43211 includes a first upper side plate 432111 and a second upper side plate 432112, the first upper side plate 432111 and the second upper side plate 432112 are located in the same plane, the first upper side plate 432111 and the second upper side plate 432112 are spaced apart from each other, the outer side surfaces of the first upper side plate 432111 and the second upper side plate 432112 respectively extend outward to form an upper extension plate 432113, the outer ends of the two upper extension plates 432113 are connected to an upper connecting plate 432114, the two ends of the upper connecting plate 432114 respectively protrude from the outer facades of the two upper extension plates 432113 to form two upper convex portions, the two upper extension plates 432113 and the upper connecting plate 432114 together form the second nesting groove 43212; the interval space between the first upper side plate 432111 and the second upper side plate 432112 forms the notch of the second nesting groove 43212, the inner facades of the two upper extension plates 432113 form the two side groove walls of the second nesting groove 43212, the outer facades of the two upper extension plates 432113 form the second connecting portion 432132, the inner side surface of the upper connecting plate 432114 forms the groove bottom wall of the second nesting groove 43212, the outer side surface of the upper connecting plate 432114 and the two upper protrusions form the second embedding head 432131 of the second nesting block 43213.

[0055] like Figure 3 As shown, the first self-recovery element 4222 is a first return spring, one end of the first return spring is pressed against the lower sliding block 421, and the other end is pressed against the inner groove wall of the lower accommodating groove after passing through each lower moving plate 4221 in sequence. The lower sliding block 421 is connected to the lower moving plate 4221 adjacent to it, and a third nesting groove 4211 is provided on the inner side of the lower sliding block 421. The notch size of the third nesting groove 4211 is smaller than the inner size of the groove, and the first embedding head 422131 on the lower moving plate 4221 adjacent to the lower sliding block 421 is embedded in the third nesting groove 4211, and the first connecting part 422132 on the lower moving plate 4221 adjacent to the lower sliding block 421 is movably passed through the notch of the third nesting groove 4211. After the lower sliding block 421 loses the pressure of the push, the first return spring can push the lower sliding block 421 outward to reset, and the lower sliding block 421 can pull each lower movable plate 4221 outward in sequence to reset. In other embodiments, the third nesting groove 4211 can be omitted, and the first nesting head 422131 can be directly bonded or welded to the lower sliding block 421. In addition, the first restoring element is not limited to the above-mentioned return spring. The first restoring portion can also be a spring edge provided between the edges of each adjacent lower movable plate 4221, such as a V-shaped spring edge located on both side edges of each adjacent lower movable plate 4221. Each adjacent lower movable plate can be directly connected by a V-shaped spring edge.

[0056] like Figure 5As shown, the second self-recovery element 4322 is a second return spring, one end of the second return spring is pressed against the upper sliding block 431, and the other end is pressed against the inner groove wall of the upper accommodating groove after passing through each upper movable plate 4321 in sequence. The upper sliding block 431 is connected to the upper movable plate 4321 adjacent to it, and a fourth nesting groove 4311 is provided on the inner side of the upper sliding block 431. The notch size of the fourth nesting groove 4311 is smaller than the inner size of the groove, and the second embedding head 432131 on the upper movable plate 4321 adjacent to the upper sliding block 431 is embedded in the fourth nesting groove 4311, and the second connecting part 432132 on the upper movable plate 4321 adjacent to the upper sliding block 431 is movably passed through the notch of the fourth nesting groove 4311. After the upper sliding block 431 loses the pressure of the push, the restoring action of the second return spring can push the upper sliding block 431 outward to reset, and the upper sliding block 431 can pull each upper movable plate 4321 outward in sequence to reset. In other embodiments, the fourth nesting groove 4311 can be omitted, and the second nesting head 432131 can be directly bonded or welded to the upper sliding block 431. In addition, the second restoring element is not limited to the above-mentioned return spring. The second restoring portion can also be a spring edge provided between each adjacent upper movable plate 4321, such as a V-shaped spring edge located on both side edges of each adjacent upper movable plate 4321. Each adjacent upper movable plate can be directly connected by a V-shaped spring edge.

[0057] like Figure 3 、 Figure 4 and Figure 9As shown, a lower guide groove 121 is formed on the side walls of the first lower accommodating groove 141 and the second lower accommodating groove 151, a first lower guide protrusion 4212 is formed at a position corresponding to the lower guide groove 121 on the lower sliding block 421, the first lower guide protrusion 4212 slides in cooperation with the lower guide groove 121, a second lower guide protrusion 42214 is formed at a position corresponding to the lower guide groove 121 on the lower movable plate 4221, the upper end of the second lower guide protrusion 42214 is supported on the top wall of the lower guide groove 121, and the lower sliding block 421 has a lower step 42 13. The lower end of the lower movable plate 4221 is abutted against the upper side surface of the lower step 4213. The inner walls of the first lower accommodating groove 141 and the second lower accommodating groove 151 are both provided with lower avoidance grooves 122. The lower avoidance grooves 122 are used to accommodate the inner ends of the corresponding lower steps 4213. The distance between the inner wall of the lower avoidance groove 122 and the inner end of the corresponding lower step 4213 is not less than the preset compression distance of each end of the steel pipe to meet the feeding demand, that is, the distance between the inner wall of the lower avoidance groove 122 and the inner end of the corresponding lower step 4213 is not less than the distance between the lower compression portion 422 when the steel pipe expansion is completed. Under the restraining effect of the lower guide groove 121, the lower sliding block 421 and the lower movable plate 4221 are not easily dislodged upward from the lower mold 12, and the lower guide groove 121 also serves as a guide, making the lower sliding block 421 and the lower movable plate 4221 more stable when moving toward or away from the fixed mold cavity 13. It is understood that in other embodiments, the lower step 4213 can be omitted, and the size of the lower movable plate 4221 can be changed so that the lower end of the lower movable plate 4221 directly abuts against the lower side wall of the corresponding lower accommodating groove.

[0058] like Figure 5 、 Figure 6 and Figure 10As shown, an upper guide groove 111 is formed on the side walls of the first upper accommodating groove 142 and the second upper accommodating groove, a first upper guide protrusion 4312 is formed at a position corresponding to the upper guide groove 111 on the upper sliding block 431, the first upper guide protrusion 4312 slides in cooperation with the upper guide groove 111, a second upper guide protrusion 43214 is formed at a position corresponding to the upper guide groove 111 on the upper movable plate 4321, the second upper guide protrusion 43214 is supported on the bottom wall of the upper guide groove 111, the upper sliding block 431 has an upper step 4313, The upper end of the upper movable plate 4321 abuts against the lower side of the upper step 4313. The inner sidewalls of the first upper accommodating groove 142 and the second upper accommodating groove 152 are each provided with an upper avoidance groove 112. The upper avoidance groove 112 is used to accommodate the inner side end of the corresponding upper step 4313. The spacing between the inner sidewall of the upper avoidance groove 112 and the inner side end of the corresponding upper step 4313 is not less than the preset compression distance at each end of the steel pipe to meet the feeding requirements. In other words, the spacing between the inner sidewall of the upper avoidance groove 112 and the inner side end of the corresponding upper step 4313 is not less than the spacing between the upper compression portion 432 when the steel pipe is bulged. The upper guide groove 111 can prevent the upper sliding block 431 and the upper movable plate 4321 from deviating downward from the upper mold 13, and the upper guide groove 111 can play a guiding role, making the upper sliding block 431 and the upper movable plate 4321 more stable when moving toward or away from the fixed mold cavity 13. It is understandable that in other embodiments, the upper step 4313 may be omitted, and the size of the upper movable plate 4321 may be changed so that the upper end of the upper movable plate 4321 directly abuts against the upper side wall of the corresponding upper receiving groove.

[0059] like Figure 2 As shown, the first blocking mechanism 2 includes a first movable push block 21 provided on the outside of the movable entry block assembly 4 at the first end side, a first sealing punch 22 provided on the inside of the first movable push block 21, and a first driving device 24. The first driving device 24 is connected to the first movable push block 21 and is used to drive the first movable push block 21 to move toward the fixed mold cavity 13. The first movable push block 21 drives the first sealing punch 22 to seal one end of the steel pipe and axially compress the corresponding movable entry block assembly 4. The sliding assembly provided on the first end side presses the compression assembly inward under the thrust of the first movable push block. The first movable push block 21 can axially compress the corresponding movable entry block assembly 4. At the same time, the first sealing punch 22 can also move with the first movable push block 21 and compress the steel pipe, so that the steel pipe can play a role of filling material during the bulging process. The first driving device 24 is a hydraulic cylinder. In other embodiments, the first driving device 24 can also be a cylinder or a push rod motor.

[0060] The second sealing mechanism 3 includes a second movable push block 31 provided on the outside of the movable entry block assembly 4 at the second end side, a second sealing punch 32 provided on the inside of the second movable push block 31, and a second drive device 33. The second drive device 33 is connected to the second movable push block 31. The second drive device 33 is used to drive the second movable push block 31 to move toward the fixed mold cavity 13. The second movable push block 31 drives the second sealing punch 32 to seal the other end of the steel pipe and axially compress the corresponding movable entry block assembly 4. The sliding assembly provided on the second end side presses the compression assembly inward under the thrust of the second movable push block. The second movable push block 31 can axially compress the corresponding movable entry block assembly 4. At the same time, the second sealing punch 32 can also move with the second movable push block 31 and compress the steel pipe, so that the steel pipe can play a role of filling material during the expansion process. The second drive device 33 is a hydraulic cylinder. In other embodiments, the second drive device 33 can also be a cylinder or a push rod motor.

[0061] The injection channel 5 can be formed on the first movable push block 21 and the first sealing punch 22 or on the second movable push block 31 and the second sealing punch 32. The injection channel can also be formed on the first movable push block 21, the first sealing punch 22 and the second movable push block 31 and the second sealing punch 32. In this specific embodiment, please continue to refer to Figure 2 The injection channel 5 is formed on the first movable push block 21 and the first sealing punch 22, and includes a first channel 51 and a second channel 52. The first channel 51 is located in the first movable push block 21, and the second channel 52 is located in the first sealing punch 22. The first end of the first channel 51 passes through the first movable push block 21 in one direction, and the second end of the first channel 51 is connected to the first end of the second channel 52. The second end of the second channel 232 passes through the first sealing punch 22 along the length direction of the first sealing punch 22. High-pressure liquid is pumped into the steel pipe through the first channel 231 and the second channel 232 to bulge the end of the steel pipe.

[0062] Example 2

[0063] A steel pipe bulging method, wherein the steel pipe is bulged using the steel pipe bulging device described in Example 1, specifically comprises the following steps:

[0064] S1, close the upper die 11 and the lower die 12 to make the steel tube to be expanded (see Figure 11 The middle part of the steel tube is located in the fixed die cavity 13, and the two ends of the steel tube to be expanded are located in the two expansion die cavities 41 respectively.

[0065] The steel tube to be expanded is placed on the lower die 12, with the two ends of the steel tube respectively located in the lower expansion cavity 411 on the two lower movable insert blocks 42, and the middle part of the steel tube is located in the lower fixed cavity 131 on the lower die 12 plate; the upper die 11 and the lower die 12 are closed, the upper fixed cavity 132 and the lower fixed cavity 131 form the fixed die cavity 13, and the upper expansion cavity 412 and the lower expansion cavity 411 form the expansion die cavity 41.

[0066] S2. The first driving device 24 of the first sealing mechanism 2 and the second driving device 33 of the second sealing mechanism 3 respectively drive the first movable push block 21 and the second movable push block 31 to move toward the fixed mold cavity 13, so that the first sealing punch 22 of the first sealing mechanism 2 and the second sealing punch 33 of the second sealing mechanism 3 are respectively pushed into the two ends of the steel pipe to seal the two ends of the steel pipe.

[0067] S3. High-pressure liquid is injected into the steel pipe through the injection channel 5 of the first plugging mechanism 2. At the same time, the first driving device 24 and the second driving device 33 continue to drive the first movable push block 21 and the second movable push block 31 to compress the two movable block assemblies inward, and the first sealing punch 22 and the second sealing punch 33 respectively compress the two ends of the steel pipe and feed the bulged part of the steel pipe. In other embodiments, when the first plugging mechanism 2 is not provided with an injection channel and only the second plugging mechanism 3 is provided with an injection channel, high-pressure liquid is injected into the steel pipe through the injection channel on the second plugging mechanism 3. When both the first plugging mechanism 2 and the second plugging mechanism 3 are provided with injection channels, high-pressure liquid can be injected into the steel pipe through the injection channel on the first plugging mechanism 2 and the injection channel on the second plugging mechanism 3 at the same time.

[0068] Specifically, high-pressure liquid is injected into the steel pipe through the first and second channels 51, 52, gradually expanding the steel pipe. At the same time, the two hydraulic cylinders are controlled to gradually drive the first movable push block 21 and the second movable push block 31 to move toward the fixed mold cavity 13. The first movable push block 21 gradually pushes the corresponding upper sliding block 431 and lower sliding block 421 toward the fixed mold cavity 13. The upper sliding block 431 compresses the upper compression portion 432, and the lower sliding block 421 compresses the lower compression portion 422. The first sealing punch 22 compresses one end of the steel pipe. The second movable push block 31 gradually pushes the corresponding upper sliding block 431 and lower sliding block 421 toward the fixed mold cavity 13. The upper sliding block 431 compresses the upper compression portion 432, and the lower sliding block 421 compresses the lower compression portion 422. The second sealing punch 32 compresses the other end of the steel pipe. This is to feed the expanded positions at both ends of the steel pipe.

[0069] S4, the first driving device 24 and the second driving device 33 respectively drive the first movable push block 21 and the second movable push block 31 to reset, so that the first sealing punch 22 and the second sealing punch 33 are reset along with the first movable push block 21 and the second movable push block 31, and the two movable block assemblies are reset, and the upper die 11 and the lower die 12 are separated to take out the bulged steel pipe (please refer to Figure 12 shown).

[0070] Specifically, after the steel tube bulging is completed, the two hydraulic cylinders are controlled to drive the first movable push block 21 and the second movable push block 31 to reset respectively, the first sealing punch 22 is reset along with the first movable push block 21, and the second sealing punch 32 is reset along with the second movable push block 31, and the corresponding lower sliding block 421 and the lower compression part 422 are reset under the action of the first reset spring, and the upper sliding block and the upper compression part 432 are reset under the action of the second reset spring. Finally, the upper die 11 and the lower die 12 are separated, and the bulged steel tube is taken out from the lower die 12 to complete the bulging of both ends of the steel tube.

[0071] During the bulging process, the two hydraulic cylinders respectively drive the first movable push block 21 and the second movable push block 31 to move toward the fixed mold cavity 13. The first movable push block 21 and the second movable push block 31 respectively compress the corresponding movable input block assembly 4, which plays the role of replenishing material while bulging, and can reduce the probability of the steel pipe being burst during the bulging process; during the bulging process, each upper movable plate 4321 and each lower movable plate 4221 can always maintain support for the pipe wall of the steel pipe, so that the part of the steel pipe located between the sliding assembly and will not be burst due to the long distance without support. After the bulged steel pipe is taken out, when the two hydraulic cylinders respectively drive the first movable push block 21 and the second movable push block 31 to reset, under the reset action of the first self-recovery element 4222 and the second self-recovery element 4322, each upper sliding block 431, each lower sliding block 421, each upper movable plate 4321 and each lower movable plate 4221 can automatically reset, which is very convenient to use.

[0072] The above embodiments merely represent preferred embodiments of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A steel tube bulging device, characterized in that: The invention comprises a bulging die formed by closing an upper die and a lower die, and a bulging mechanism; a fixed die cavity for accommodating the middle part of the steel pipe, and a movable block assembly located in the accommodating space at both ends of the fixed die cavity are formed in the bulging die, and a bulging die cavity for accommodating the corresponding end parts of the steel pipe is formed on the movable block assembly; the bulging mechanism comprises a first blocking mechanism provided on the first end side of the bulging die for blocking the first end of the steel pipe, a second blocking mechanism formed on the second end side of the bulging die for blocking the second end of the steel pipe, and an injection channel formed on the first blocking mechanism and / or the second blocking mechanism and used for injecting high-pressure liquid into the steel pipe, the first blocking mechanism and the second blocking mechanism being used to compress the two movable block assemblies respectively; The movable block assembly includes a self-recovering compression assembly arranged in the corresponding accommodation space and a sliding assembly slidingly fitted in the corresponding accommodation space and located outside the compression assembly; The first blocking mechanism and the second blocking mechanism each include a movable push block provided on the outside of the corresponding movable entry block assembly, a sealing punch provided on the movable push block, and a driving device connected to the movable push block, the driving device being used to drive the movable push block to move toward the fixed mold cavity to axially compress the sliding assembly, and the sliding assembly presses the compression assembly inward under the thrust of the movable push block; The movable push block drives the sealing punch to seal and compress the ends of the steel pipe respectively to feed the bulged part of the steel pipe; The compression assembly includes a plurality of movable plates that are sleeved layer by layer from the inside to the outside and a self-recovering component located between each two adjacent movable plates to automatically reset each movable plate; there is a predetermined compression spacing between each two adjacent movable plates when they are not pressed by the sliding assembly, and the sum of all compression spacings is adapted to the size of the material that needs to be replenished during the steel pipe expansion process; the compression spacing between each two adjacent movable plates gradually decreases under the pressure of the sliding assembly until the movable plates are stacked together, so that during the expansion process at both ends of the steel pipe, the steel pipe ends are supported by the plurality of movable plates, and the distributed compression spacings divide the distance between the sliding assembly and the fixed mold cavity into several parts, thereby preventing the steel pipe from being burst due to the excessive distance between the sliding assembly and the fixed mold cavity.

2. A steel tube bulging device according to claim 1, characterized in that: The first end side position of the lower mold is provided with a first lower accommodating groove formed by being recessed downwardly, and the second end side position of the lower mold is provided with a second lower accommodating groove formed by being recessed downwardly, the first lower accommodating groove and the second lower accommodating groove respectively penetrate the lower mold in opposite directions, and the first lower accommodating groove and the second lower accommodating groove are both provided with lower movable insertion blocks; the lower end surface of the upper mold is formed with a first upper accommodating groove adapted to the position of the first lower accommodating groove, and the lower end surface of the upper mold is formed with a second upper accommodating groove adapted to the position of the second lower accommodating groove, and the first upper accommodating groove and the second upper accommodating groove are both provided with upper movable insertion blocks; The first lower accommodating groove and the first upper accommodating groove form a first accommodating space in the mold closing state, and the second lower accommodating groove and the second upper accommodating groove form a second accommodating space in the mold closing state; the lower movable entry block in the first lower accommodating groove and the upper movable entry block in the first upper accommodating groove form a movable entry block assembly located in the first accommodating space in the mold closing state, and the lower movable entry block in the second lower accommodating groove and the upper movable entry block in the second upper accommodating groove form a movable entry block assembly located in the second accommodating space in the mold closing state.

3. A steel tube bulging device according to claim 2, characterized in that: A lower fixed cavity is formed on the upper end surface of the lower mold at a position between the first lower accommodating groove and the second lower accommodating groove, and two ends of the lower fixed cavity are respectively communicated with the first lower accommodating groove and the second lower accommodating groove; an upper fixed cavity is formed on the lower end surface of the upper mold at a position between the first upper accommodating groove and the second upper accommodating groove, and two ends of the upper fixed cavity are respectively communicated with the first upper accommodating groove and the second upper accommodating groove; the lower fixed cavity and the upper fixed cavity form the fixed mold cavity in the mold closing state.

4. A steel tube bulging device according to claim 3, characterized in that: The lower movable entry block includes a lower sliding block arranged in the corresponding lower accommodating groove and a lower compression part arranged between the lower sliding block and the lower fixed cavity, and the lower sliding block can slide toward the fixed mold cavity and compress the lower compression part; the upper movable entry block includes an upper sliding block arranged in the corresponding upper accommodating groove and an upper compression part arranged between the upper sliding block and the upper fixed cavity, and the upper sliding block can slide toward the fixed mold cavity and compress the upper compression part; the lower sliding block and the upper sliding block form the sliding assembly in the mold closing state, and the lower compression part and the upper compression part form the compression assembly in the mold closing state.

5. A steel tube bulging device according to claim 4, characterized in that: The lower compression part includes a plurality of lower movable plates located between the lower sliding block and the lower fixed cavity and a first self-recovering element located between each two adjacent lower movable plates, and a lower compression gap is provided between each two adjacent lower movable plates; the upper compression part includes a plurality of upper movable plates located between the upper sliding block and the upper fixed cavity and a second self-recovering element located between each two adjacent upper movable plates, and an upper compression gap is provided between each two adjacent upper movable plates; the upper movable plate and the lower movable plate form the movable plate in the mold closing state, and the first self-recovering element and the second self-recovering element form the self-recovering component in the mold closing state.

6. A steel tube bulging device according to claim 5, characterized in that: The first self-recovery element is a first return spring, one end of the first return spring is pressed against the lower sliding block, and the other end is pressed against the inner groove wall of the first lower accommodating groove or the second lower accommodating groove after passing through each lower moving plate in sequence, and the lower sliding block is connected to the lower moving plate adjacent to it; the second self-recovery element is a second return spring, one end of the second return spring is pressed against the upper sliding block, and the other end is pressed against the inner groove wall of the first upper accommodating groove or the second upper accommodating groove after passing through each upper moving plate in sequence, and the upper sliding block is connected to the upper moving plate adjacent to it.

7. The steel tube bulging device according to claim 5, characterized in that: The lower movable plate includes a lower stacking plate, a first nesting groove formed on the inner side of the lower stacking plate, and a first nesting block formed on the outer side of the lower stacking plate, wherein the notch size of the first nesting groove is smaller than the inner size of the groove; the first nesting block includes a first inserting head embedded in the first nesting groove and a first connecting portion connected between the first inserting head and the lower stacking plate and movably provided at the notch of the first nesting groove, wherein the thickness of the first inserting head is smaller than the depth of the first nesting groove, and the thickness of the first connecting portion is larger than the depth of the notch of the first nesting groove; The upper movable plate includes an upper stacking plate, a second nesting groove formed on the inner side of the upper stacking plate, and a second nesting block formed on the outer side of the upper stacking plate, the slot size of the second nesting groove is smaller than the slot inner size; the second nesting block has a second embedding head embedded in the second nesting groove and a second connecting part connected between the second embedding head and the upper stacking plate and movably passed through the slot of the second nesting groove, the thickness of the second embedding head is smaller than the depth of the second nesting groove, and the thickness of the second connecting part is greater than the depth of the slot of the second nesting groove.

8. A steel tube bulging device according to claim 7, characterized in that: The two cams are connected to each other by a plurality of latches, and the two cams are connected to each other by a plurality of latches, and the plurality of latches are connected to each other by a plurality of latches. The upper stacking plate includes a first upper side plate and a second upper side plate located in the same plane and spaced apart from each other, the outer side surfaces of the first upper side plate and the second upper side plate respectively extending outward to form an upper extension plate, the outer ends of the two upper extension plates are connected to an upper connecting plate, the two ends of the upper connecting plate respectively protrude from the outer facades of the two upper extension plates to form two upper convex portions, and the two upper extension plates and the upper connecting plate enclose to form the second nesting groove; the spacing space between the first upper side plate and the second upper side plate forms the notch of the second nesting groove, the inner facades of the two upper extension plates form the two side groove walls of the second nesting groove, the outer facades of the two upper extension plates form the second connecting portion, the inner side surface of the upper connecting plate forms the groove bottom wall of the second nesting groove, and the outer side surface of the upper connecting plate and the two upper convex portions form the second embedding head of the second nesting block.

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