Free bending forming device and method for metal pipe

Abstract

The invention relates to a metal pipe free bending forming device and method, and relates to the technical field of metal pipe bending forming, the metal pipe free bending forming device comprises a bending ball die, a pipe channel is arranged, and an annular protrusion used for metal pipe bending forming is arranged in the pipe channel. The supporting structure is located in the pipe channel and comprises a plurality of branch structures arranged in the axial direction of the pipe channel; the inner side of the supporting ring is used for being matched with the outer wall of the metal pipe; the elastic piece is arranged between the outer side of the supporting ring and the inner wall of the pipe channel and used for connecting the supporting ring into the pipe channel in a floating mode. An annular protrusion is used for driving a metal pipe to be bent under the action of an external driving device; the supporting structure can provide annular supporting for the metal pipe before the metal pipe enters the annular protrusion and under the scene that the deflection angle of the bending ball die may change, and the problems of pipe wall breakage, pipe section distortion, pipe wall bending part wrinkling and the like are reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of metal tube bending forming, and particularly to a device and method for free bending forming of metal tubes. Background Art

[0002] In the fields of aerospace, automobile manufacturing, and high-end equipment, thin-walled metal tubes have attracted much attention due to their characteristics such as light weight, high strength, and resistance to high temperature and high pressure.

[0003] Chinese Patent CN207615432U discloses a new bending die required for a three-dimensional free bending forming process, which includes a hard insert, an outer sphere, a tail connection section, and an oil injection hole. The hard insert is installed in the outer sphere by interference fit, and the tail connection section is installed in the outer sphere by threaded connection. In the mechanism assembly, the outer sphere cooperates with a spherical bearing, and the tail connection section is in spherical contact with the guiding mechanism. Before the tube bending forming process, an appropriate amount of lubricating oil is added to the oil injection hole. During the tube bending forming process, the outer sphere undergoes a translational displacement driven by the spherical bearing, the tail connection section controls the rotation angle of the bending die through spherical contact with the guiding mechanism, and the hard insert acts on the tube to make it bend and deform.

[0004] In the above-mentioned bending die, there is a relatively long channel at the connection between the guiding mechanism and the bending ball die, and this channel has no supporting effect on the metal tube wall, resulting in the metal tube being subjected to non-uniform loads in this channel, making it easy for the metal tube to have problems such as tube wall rupture, tube cross-section distortion, and wrinkling of the bent part of the tube wall during the forming process. Summary of the Invention

[0005] Aiming at the problems in the prior art that there is a relatively long channel at the connection between the guiding mechanism and the bending ball die, which has no supporting effect on the metal tube wall, resulting in problems such as tube wall rupture, tube cross-section distortion, and wrinkling of the bent part of the tube wall during the metal tube bending forming, the present invention provides a device and method for free bending forming of metal tubes, and a supporting structure for uniformly floating support of the tube wall is provided at the connection between the guiding mechanism and the bending ball die to reduce the occurrence of problems such as tube wall rupture, tube cross-section distortion, and wrinkling of the bent part of the tube wall during the metal tube bending forming process.

[0006] The present invention provides a device for free bending forming of metal tubes, including:

[0007] A bending ball die, provided with a tube channel, and an annular protrusion for metal tube bending forming is arranged in the tube channel.

[0008] A supporting structure, located in the tube channel, includes a plurality of branch structures arranged along the axial direction of the tube channel. The branch structure includes: a support ring, the inner side of which is used to cooperate with the outer wall of the metal tube; an elastic member, arranged between the outer side of the support ring and the inner wall of the tube channel, for floatingly connecting the support ring in the tube channel.

[0009] In some of these embodiments, the support structure further includes: an assembly ring located outside all the branch structures and connected to all the elastic members.

[0010] In some of these embodiments, the assembly ring is in mating engagement with the spherical surface of the bending ball mold to enable the free rotation of the assembly ring within the bending ball mold.

[0011] In some of these embodiments, the elastic members are springs, and multiple springs are arranged around the axis of the support ring in each branch structure.

[0012] In some of these embodiments, the branch structure further includes: ball hinges, corresponding one-to-one with the springs, for connecting the corresponding springs to the assembly ring.

[0013] In some of these embodiments, two adjacent support rings are slidably connected, and the sliding direction is perpendicular to the axis of the support ring.

[0014] In some of these embodiments, the branch structure further includes: an elastic layer attached to the inner side of the support ring.

[0015] In some of these embodiments, the metal tube free bending forming device further includes: an elastic blocking structure arranged between the annular protrusion and the support structure, and abutting against the support ring adjacent to the annular protrusion and the bending ball mold on both sides respectively.

[0016] In some of these embodiments, the metal tube free bending forming device further includes:

[0017] A positioning structure located on the side of the support structure away from the annular protrusion, in mating engagement with the spherical surface of the bending ball mold to enable the free rotation of the bending ball mold relative to the positioning structure.

[0018] A guiding structure installed within the positioning structure, adjustable in position in the axial direction of the positioning structure, and having a tube guiding channel communicating with the tube forming channel.

[0019] The present invention also provides a method for free bending and forming a metal tube, which uses the above-mentioned metal tube free bending forming device to perform free bending and forming of the metal tube.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] 1. The metal tube passes through all the support rings and the annular protrusion, and travels within the bending ball mold along the direction from the support structure to the annular protrusion. During the travel of the metal tube, all the support rings are arranged along the length direction of the metal tube and circumferentially hold the metal tube. Under the action of the elastic members, the positions of all the support rings can be correspondingly changed along with the bending angle of the metal tube to achieve universal support for the metal tube at different deflection angles of the bending ball mold, reducing the occurrence of problems such as tube wall rupture, tube cross-section distortion, and wrinkling of the bent part of the tube wall.

[0022] 2. The general assembly ring rotates freely within the bending spherical mold, and the support ring is connected to the general assembly ring through a spherical hinge. Both of the above methods can improve the deflection flexibility of the support ring, which helps the support ring to always provide circumferential support for the pipe along the radial direction of the pipe. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings described herein are used to provide a further understanding of the present invention and form a part of this application. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0024] Figure 1 is a schematic diagram of the support structure in the present invention;

[0025] Figure 2 is a schematic diagram of the metal pipe free bending forming device in the present invention;

[0026] Figure 3 is Figure 2 an enlarged schematic diagram of area A in

[0027] Figure 4 is Figure 3 an enlarged schematic diagram of area B in

[0028] Figure 5 is a schematic diagram showing the protrusion in the present invention.

[0029] In the drawings:

[0030] 1. Bending spherical mold; 11. Annular protrusion; 2. Support structure; 211. Support ring; 212. Spring; 213. Ball head; 214. Ball seat; 215. Mounting seat; 22. General assembly ring; 23. Sliding assembly; 231. Connecting body; 232. Insertion ring; 24. Elastic layer; 3. Elastic blocking structure; 31. Connecting part; 32. Abutting part; 4. Positioning structure; 5. Guiding structure; 6. Limiting body. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] Next, the technical solutions in the embodiments will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0032] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "center", "lateral", "longitudinal", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings. These are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention.

[0033] The terms "first", "second", "third" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first", "second", "third" may explicitly or implicitly include one or more of such features.

[0034] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "connected", "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] As Figures 1-5 shown, in a schematic embodiment of the metal tube free bending forming device of the present invention, the metal tube free bending forming device at least includes:

[0036] A bending ball die 1 is provided with a pipe channel, and an annular protrusion 11 for bending and forming the metal tube is arranged in the pipe channel.

[0037] A support structure 2 is located in the pipe channel and includes a plurality of branch structures arranged along the axial direction of the pipe channel. The branch structure includes: a support ring 211, the inner side of which is used to cooperate with the outer wall of the metal tube; an elastic member is arranged between the outer side of the support ring 211 and the inner wall of the pipe channel for floatingly connecting the support ring 211 in the pipe channel.

[0038] When the above metal tube free bending forming device is in use, the metal tube passes through all the support rings 211 and the annular protrusion 11, and travels in the bending ball die 1 along the direction from the support structure 2 to the annular protrusion 11. During the traveling of the metal tube, all the support rings 211 are arranged along the length direction of the metal tube and circumferentially hold the metal tube. Under the action of the elastic member, the positions of all the support rings 211 can be correspondingly changed along with the bending angle of the metal tube to achieve universal support for the metal tube at different deflection angles of the bending ball die 1, and reduce the occurrence of problems such as pipe wall rupture, pipe cross-section distortion, and wrinkling in the bent part of the pipe wall.

[0039] Further, it is preferable to set three or more branch structures.

[0040] In some embodiments, the support structure 2 further includes: an assembly ring 22, located outside all the branch structures and connected to all the elastic members. The assembly ring 22 is used to integrate all the branch structures, reducing the difficulty of connecting the support structure 2 to the bending ball mold 1.

[0041] In some embodiments, the assembly ring 22 is in spherical fit with the spherical surface of the bending ball mold 1 to achieve the free rotation of the assembly ring 22 within the bending ball mold 1, thereby improving the deflection flexibility of the support ring 211, enabling the support ring 211 to always provide circumferential support for the pipe along the radial direction of the pipe.

[0042] In some embodiments, the elastic member is a spring 212, and a plurality of springs 212 are arranged around the axis of the support ring 211 in each branch structure.

[0043] Further, all the springs 212 in the branch structure are evenly distributed around the axis of the support ring 211.

[0044] Further, it is preferable to set four or more springs 212 in the branch structure.

[0045] Further, the elastic modulus of the spring 212 is 100 - 120 GPa to improve the support effect of the spring 212 on the metal pipe, further reducing the occurrence of problems such as pipe wall rupture, pipe cross-section distortion, and wrinkling in the bent part of the pipe wall.

[0046] Further, the material of the spring 212 is preferably beryllium copper alloy, which has high toughness, high strength, high fatigue limit, and is suitable for the high-temperature working conditions of electric-assisted pipe bending forming.

[0047] In some embodiments, the branch structure further includes: ball joints, corresponding to the springs 212 one by one, for connecting the corresponding springs 212 to the assembly ring 22. The ball joints can improve the deflection flexibility of the support ring 211, enabling the support ring 211 to always provide circumferential support for the pipe along the radial direction of the pipe.

[0048] Further, the ball joint includes:

[0049] A ball head 213, fixed inside the assembly ring 22.

[0050] A ball seat 214, in spherical fit with the ball head 213 and connected to the spring 212.

[0051] Further, all the ball heads 213 and the assembly ring 22 are integrally formed to improve the connection strength between the ball head 213 and the assembly ring 22.

[0052] Further, the branch structure further includes: mounting seats 215, corresponding to the springs 212 one by one, and fixed on the outer side of the support ring 211. Both ends of each spring 212 are respectively connected to its corresponding ball seat 214 and mounting seat 215.

[0053] Further, steps for limiting the movement of the spring 212 are provided on both the ball seat 214 and the mounting seat 215. The steps are divided into two layers with different diameters. The layer with a smaller diameter is inserted into the spring 212 to cooperate with the inner side of the spring 212, and the layer with a larger diameter abuts against the end of the spring 212 to limit the spring 212.

[0054] Further, each support ring 211 is integrally formed with all its corresponding protrusions to improve the connection strength between the support ring 211 and the protrusions.

[0055] In some embodiments, two adjacent support rings 211 are slidably connected, and the sliding direction is perpendicular to the axis of the support ring 211 to ensure that all support rings 211 are parallel to each other and avoid the situation where the support structure 2 jams the metal pipe due to an angle greater than 0° between two support rings 211.

[0056] Further, the inner circumferential edges of the support rings 211 are all rounded to prevent abrasion of the outer wall of the metal pipe.

[0057] Further, there is a certain amount of movement allowance between two adjacent support rings 211 in the direction parallel to the axis of the support ring 211, and there is a certain amount of movement allowance between two adjacent support rings 211 in the direction perpendicular to the axis of the support ring 211 to prevent two adjacent support rings 211 from being stuck.

[0058] Further, the movement allowance between two adjacent support rings 211 in the direction parallel to the axis of the support ring 211 is less than or equal to 1 mm, and the movement allowance between two adjacent support rings 211 in the direction perpendicular to the axis of the support ring 211 is less than or equal to 3 mm.

[0059] Further, the support structure 2 further includes a sliding assembly 23. The sliding assembly 23 includes a connecting body 231 and a plugging ring 232. Two plugging rings 232 are provided between two adjacent support rings 211. The two plugging rings 232 are respectively connected to the two support rings 211 through two connecting bodies 231. One plugging ring 232 and the support ring 211 it is connected to are inserted into the other plugging ring 232 to achieve the sliding connection between two adjacent support rings 211.

[0060] In some embodiments, all branch structures are evenly distributed along the axis of the general assembly ring 22.

[0061] In some of these embodiments, the branch structure further includes: an elastic layer 24, attached to the inner side of the support ring 211. When the metal tube free bending and forming device is in use, the elastic layer 24 is located between the support ring 211 and the metal tube, which helps to improve the adaptability of the branch structure to slight changes in the pipe diameter and enhances the circumferential wrapping and supporting effect of the support ring 211 on the metal tube.

[0062] Further, the elastic layer 24 is a rubber layer.

[0063] In some of these embodiments, there is a gap between one side of the support structure 2 close to the annular protrusion 11 and the bending ball mold 1 to increase the deflection space of the support structure 2.

[0064] Further, the metal tube free bending and forming device further includes: an elastic blocking structure 3, disposed between the annular protrusion 11 and the support structure 2, and abutting against the support ring 211 adjacent to the annular protrusion 11 and the bending ball mold 1 on both sides respectively. The elastic blocking structure 3 is used to prevent the support structure 2 from excessively shifting towards the direction close to the annular protrusion 11, helps the metal tube quickly disengage from the support structure 2, and at the same time speeds up the reset speed of the support structure 2.

[0065] Further, a plurality of elastic blocking structures 3 are arranged around the axis of the bending ball mold 1.

[0066] Further, all the elastic blocking structures 3 are evenly distributed around the axis of the bending ball mold 1.

[0067] Further, the elastic blocking structure 3 is a rigid thin sheet, including a connecting portion 31 and an abutting portion 32 fixedly connected. The connecting portion 31 is detachably or fixedly connected to the bending ball mold 1, and the abutting portion 32 inclines towards the direction close to the axis of the bending ball mold 1 and abuts against the adjacent support ring 211. The connecting portion 31 is perpendicular to the axis of the bending ball mold 1, and the angle between the connecting portion 31 and the abutting portion 32 is an acute angle or an obtuse angle. Figure 3 In [it], the angle between the connecting portion 31 and the abutting portion 32 is an obtuse angle.

[0068] Further, the connecting portion 31 and the abutting portion 32 are integrally formed to improve the structural strength of the elastic blocking structure 3.

[0069] Further, the elastic modulus of the elastic blocking structure 3 is preferably 180 - 210 GPa, and the material is preferably spring 212 steel.

[0070] Further, all the elastic blocking structures 3 are evenly distributed around the axis of the bending ball mold 1.

[0071] In some of these embodiments, the metal tube free bending and forming device further includes:

[0072] The positioning structure 4 is located on the side of the support structure 2 away from the annular protrusion 11 and is in spherical cooperation with the bending ball mold 1, enabling the bending ball mold 1 to rotate freely relative to the positioning structure 4.

[0073] The guiding structure 5 is installed inside the positioning structure 4 and is adjustable in position in the axial direction of the positioning structure 4. It has a pipe guiding channel communicating with the pipe forming channel.

[0074] The minimum bending radius of the metal pipe is determined by the distance between the end of the guiding structure 5 close to the annular protrusion 11 and the annular protrusion 11. The smaller the distance between the two, the smaller the minimum bending radius of the metal pipe. Therefore, by changing the position of the guiding structure 5 in the axial direction of the positioning structure 4, the minimum bending radius of the metal pipe can be adjusted.

[0075] The connection method between the guiding structure 5 and the positioning structure 4 includes but is not limited to threaded connection, bonding, and clamping connection.

[0076] Further, the metal pipe free bending forming device further includes: a limiting body 6, which is fixed on the outer side of the guiding structure 5 and is located on the side of the positioning structure 4 away from the support structure 2. When the limiting body 6 abuts against the positioning structure 4, the guiding structure 5 cannot move towards the direction close to the support structure 2, so as to prevent the guiding structure 5 from hitting the support structure 2.

[0077] Further, the limiting body 6 and the guiding structure 5 are integrally formed to improve the connection strength between the limiting body 6 and the guiding structure 5.

[0078] Further, the limiting body 6 is annularly fixed on the outer side of the guiding structure 5.

[0079] Further, the outer edge of one end of the guiding structure 5 close to the support structure 2 is chamfered to facilitate the insertion of the guiding structure 5 into the support structure 2.

[0080] The present invention also provides a method for free bending forming of a metal pipe, which uses the above metal pipe free bending forming device to perform free bending forming of the metal pipe. In the metal pipe free bending forming device, the annular protrusion 11 annularly clamps the metal pipe, and the annular protrusion 11 is used to drive the metal pipe to bend under the action of an external driving device; the support structure 2 can provide circumferential support for the metal pipe in a scenario where the deflection angle of the bending ball mold 1 may change before the metal pipe enters the annular protrusion 11, reducing the occurrence of problems such as pipe wall rupture, pipe cross-section distortion, and wrinkling of the bent part of the pipe wall.

[0081] Through the description of multiple embodiments of the metal pipe free bending forming device of the present invention, it can be seen that the embodiments of the metal pipe free bending forming device of the present invention have at least one or more of the following advantages:

[0082] 1. The metal pipe passes through all the support rings 211 and the annular protrusion 11, and travels within the bending spherical die 1 along the direction from the support structure 2 to the annular protrusion 11. During the travel of the metal pipe, all the support rings 211 are arranged along the length direction of the metal pipe and hold the metal pipe circumferentially. Under the action of the elastic member, the positions of all the support rings 211 can be correspondingly changed along with the bending angle of the metal pipe, so as to achieve universal support for the metal pipe at different deflection angles of the bending spherical die 1, and reduce the occurrence of problems such as pipe wall rupture, pipe cross-section distortion, and wrinkling of the bent part of the pipe wall.

[0083] 2. The general assembly ring 22 rotates freely within the bending spherical die 1, and the support ring 211 is connected to the general assembly ring 22 through a spherical hinge. Both of the above two means can improve the deflection flexibility of the support ring 211, which helps the support ring 211 to always provide circumferential support for the pipe along the radial direction of the pipe material.

[0084] Finally, it should be noted that: the embodiments in this specification are described in a progressive manner, and the key point of each embodiment is to illustrate the differences from other embodiments. For the same or similar parts among the embodiments, reference can be made to each other.

[0085] The above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it; although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that: still can modify the specific implementation manners of the present invention or make equivalent replacements for some technical features; without departing from the spirit of the technical solutions of the present invention, they should all be covered within the scope of the technical solutions claimed by the present invention.

Claims

1. A metal tube free bending forming device, characterized in that: include: The bending ball mold is provided with a pipe channel, and an annular protrusion for bending and forming the metal pipe is provided in the pipe channel; The support structure is located in the pipe channel and includes a plurality of branch structures arranged along the axial direction of the pipe channel; the branch structure includes: a support ring, the inner side of which is used to match the outer wall of the metal pipe; an elastic member, which is arranged between the outer side of the support ring and the inner wall of the pipe channel and is used to float the support ring in the pipe channel.

2. The metal tube free bending forming device according to claim 1, characterized in that: The supporting structure also includes: a general assembly ring, which is located outside all branch structures and connected to all elastic parts.

3. The metal tube free bending forming device according to claim 2, characterized in that: The final assembly ring cooperates with the spherical surface of the curved ball mold to realize the free rotation of the final assembly ring in the curved ball mold.

4. The metal tube free bending forming device according to claim 2, characterized in that: The elastic member is a spring, and a plurality of springs are arranged around the axis of the support ring in each branch structure.

5. The metal tube free bending forming device according to claim 4, characterized in that: The branch structure also includes: a ball joint, which corresponds to the spring one by one and is used to connect the corresponding spring to the assembly ring.

6. The metal tube free bending forming device according to any one of claims 1 to 5, characterized in that: Two adjacent support rings are connected in a sliding manner, and the sliding direction is perpendicular to the axial direction of the support rings.

7. The metal tube free bending forming device according to any one of claims 1 to 5, characterized in that: The branch structure also includes: an elastic layer attached to the inner side of the supporting ring.

8. The metal tube free bending forming device according to any one of claims 1 to 5, characterized in that: Also includes: The elastic blocking structure is arranged between the annular protrusion and the supporting structure, and the two sides thereof are respectively abutted against the supporting ring and the curved ball mold adjacent to the annular protrusion.

9. The metal tube free bending forming device according to any one of claims 1 to 5, characterized in that: Also includes: The positioning structure is located at a side of the supporting structure away from the annular protrusion and cooperates with the spherical surface of the curved ball mold so that the curved ball mold can rotate freely relative to the positioning structure; The guide structure is installed in the positioning structure, the position in the axial direction of the positioning structure is adjustable, and has a pipe guide channel connected with the pipe forming channel.

10. A method for forming a metal tube by free bending, characterized in that: The free bending forming device for a metal tube according to any one of claims 1 to 9 is used to perform free bending forming of a metal tube.

Images