An apparatus and method for press bending of an ultra-thin-walled metal tube

Abstract

The application provides an ultra-thin-wall metal pipe press bending forming device and method, which solves the technical problems of wrinkles on the inner side and excessive thinning on the outer side of the pipe in the prior art when manufacturing an ultra-thin-wall bent pipe; a pair of pulling clamping devices are arranged on the pulling clamping mechanism, and a pair of pushing clamping devices are arranged on the pushing clamping mechanism, which are arranged on the two sides of the upper and lower die plates; the pulling clamping device is provided with a first clamp, the first clamp is hinged to a first connecting rod assembly, the first connecting rod assembly is hinged to a first support frame, and the first connecting rod assembly is in a straight state; the pushing clamping device is provided with a second clamp, the second clamp is hinged to a second connecting rod assembly, the second connecting rod assembly is hinged to a second support frame, and the second connecting rod assembly is in a bent state; the lower die mechanism is provided with a pair of left and right spaced lower die plates, the lower die plate is provided with an arc-shaped straight-through groove; the lower die plate is provided with a hinged rotating shaft, the outer side of the lower die plate is connected with a connecting rod, and the connecting rod is connected with a limiting spring; the application also provides a press bending forming method, and can be widely applied to the technical field of metal pipe forming.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of metal pipe forming, in particular to a bending forming device and method for an extremely thin-wall metal pipe. BACKGROUND

[0002] With the development of modern industrial technology, thin-wall metal pipe parts are widely used in industrial products due to light weight, small amount and compact structure. At present, parts manufactured by bending thin-wall metal pipes are widely used in the fields of aerospace, automobiles and electronics as gas and liquid conveying pipelines. Therefore, the bending forming technology of thin-wall metal pipes plays a crucial role in the development of high-end manufacturing industry.

[0003] The thin-wall metal pipe has a thin wall thickness, usually between several millimeters and several microns. The bending forming of the thin-wall metal pipe is a metal processing method, which usually adopts hydraulic or mechanical bending equipment to bend and deform the thin-wall metal pipe by applying a certain pressure or torque to form a required shape. The invention disclosed in the publication No. CN113182404A discloses a bending device for a thin-wall metal pipe, which comprises an inner support, an upper die and a lower die. The die cavity of the upper die and the lower die in the closed die state is matched with the bent metal pipe. The inner support is matched with the pipe cavity of the metal pipe. The inner support comprises a plurality of support beads connected in series on a soft rod through a through hole, and the diameter of the support bead matches the inner diameter of the pipe cavity. A plurality of sliding beads with a diameter larger than that of the through hole are arranged on the soft rod at intervals, and the sliding beads are arranged in the sliding cavity along the through hole. The center point of the soft rod is taken as the center point. When the inner support is matched with the bent metal pipe, the support beads are sequentially adjacent, and the sliding beads are arranged on one side of the sliding cavity near the center point. The inner support plays a role of supporting, preventing deformation and assisting bending for the metal pipe. By introducing lubricating liquid on the contact surface, the friction between the contact surfaces is reduced, and the thin wall of the metal pipe is protected. The fixed ring limits the metal pipe to ensure the stability of the bending, prevent excessive deformation of the two ends of the pipe, improve the bending precision, and has strong practicality and wide applicability.

[0004] However, the above-mentioned invention is not suitable for bending of an extremely thin-wall metal pipe. The relative wall thickness reciprocal d / t of the extremely thin-wall metal pipe is greater than 40 (d is the outer diameter of the pipe material, unit: mm; t is the thickness of the pipe material, unit: mm). When the extremely thin-wall metal pipe with a small relative bending radius is bent using the above-mentioned technical solution, wrinkles will appear on the inner side of the pipe and the outer side will be excessively thinned, which cannot meet the bending production needs of the extremely thin-wall bent pipe. This technical problem needs to be solved urgently. SUMMARY

[0005] The purpose of the present application is to solve the above technical problems, and provide a bending forming device and method for an extremely thin-wall metal pipe to meet the production needs of the extremely thin-wall bent pipe.

[0006] To this end, the present application provides a kind of very thin wall metal pipe bending forming device, bending forming device is equipped with upper die mechanism, lower die mechanism, upper die mechanism is equipped with upper die plate, lower die mechanism is equipped with lower die plate, lower die plate is spaced below upper die plate, the die cavity of upper die mechanism and lower die mechanism in closed die state is adapted to the metal pipe after bending forming;Bending forming device is also equipped with pulling clamping mechanism and pushing clamping mechanism, pulling clamping mechanism is spaced above pushing clamping mechanism.

[0007] Pulling clamping mechanism is equipped with a pair of pulling clamping devices, which are respectively arranged on the left and right sides of upper die plate and lower die plate;Pulling clamping device is equipped with first clamp, first connecting rod assembly, first support frame, first clamp is hingedly connected with first connecting rod assembly, first connecting rod assembly is hingedly connected with first support frame;The initial state of first connecting rod assembly is straightened state.

[0008] Pushing clamping mechanism is equipped with a pair of pushing clamping devices, which are respectively arranged on the left and right sides of upper die plate and lower die plate;Pushing clamping device is equipped with second clamp, second connecting rod assembly, second support frame, second clamp is hingedly connected with second connecting rod assembly, second connecting rod assembly is hingedly connected with second support frame;The initial state of second connecting rod assembly is bent state.

[0009] Lower die mechanism is equipped with a pair of lower die plates, a pair of lower die plates are spaced left and right, and are symmetrically arranged relative to upper die plate;Lower die plate is equipped with arc straight-through slot with opening upward, and arc straight-through slot is used to limit very thin wall metal pipe;The bottom of lower die plate is provided with hinged rotating shaft, and the outer side of lower die plate is fixedly connected with connecting rod, and connecting rod is connected with limiting spring.

[0010] Preferably, first connecting rod assembly is equipped with first connecting rod and second connecting rod;One end of first connecting rod is hingedly connected with first clamp, the other end of first connecting rod is hingedly connected with one end of second connecting rod, and the other end of second connecting rod is hingedly connected with first support frame;The included angle between first connecting rod and second connecting rod is 180° in initial state.

[0011] Preferably, first support frame is telescopic rod with locking structure, and the extending rod of first support frame is hingedly connected with first connecting rod assembly.

[0012] Preferably, first clamp is provided with first half-ring-shaped through slot for inserting the upper side of the end of very thin wall metal pipe.

[0013] Preferably, first clamp is provided with outer semicircular clasp and inner semicircular clasp, the two ends of outer semicircular clasp respectively extend outward to form first connecting part, and the two ends of inner semicircular clasp respectively extend outward to form second connecting part;Outer semicircular clasp and inner semicircular clasp are in the same direction, and are arranged in a stack, first connecting part and second connecting part are detachably connected, and a half-ring-shaped groove is formed between outer semicircular clasp and inner semicircular clasp;Outer semicircular clasp is hingedly connected with first connecting rod assembly.

[0014] Preferably, the second linkage assembly is provided with a third linkage and a fourth linkage; one end of the third linkage is hingedly connected with the second clamp, the other end of the third linkage is hingedly connected with one end of the fourth linkage, the other end of the fourth linkage is hingedly connected with the second support frame; the included angle between the third linkage and the fourth linkage in the initial state is not equal to 180°.

[0015] Preferably, the second support frame is a telescopic rod with a locking structure, and the extending rod of the second support frame is hingedly connected with the second linkage assembly.

[0016] Preferably, a second half-ring-shaped through groove is formed on the second clamp for inserting and fixing the lower side of the end of the extremely thin-walled metal pipe.

[0017] Preferably, the first linkage assembly is provided with a first cylinder and a first telescopic rod with a locking structure; the piston rod of the first cylinder is hingedly connected with the first clamp, the cylinder body of the first cylinder is hingedly connected with the telescopic rod end of the first telescopic rod, the tail rod of the first telescopic rod is hingedly connected with the first support frame, and the included angle between the first cylinder and the first telescopic rod in the initial state is 180°.

[0018] Preferably, the second linkage assembly is provided with a second cylinder and a second telescopic rod; the piston rod of the second cylinder is hingedly connected with the second clamp, the cylinder body of the second cylinder is hingedly connected with the telescopic rod end of the second telescopic rod, the tail rod of the second telescopic rod is hingedly connected with the second support frame, and the included angle between the second cylinder and the second telescopic rod in the initial state is not equal to 180°.

[0019] A method for bending and forming an extremely thin-walled metal pipe, using the bending and forming device for an extremely thin-walled metal pipe according to any one of the preceding claims, comprising the following steps:

[0020] Step S1. Obtain the extremely thin-walled metal pipe to be bent, and insert the polyurethane mandrel into the extremely thin-walled metal pipe to prepare for bending and forming the extremely thin-walled metal pipe;

[0021] Step S2. Open the mold, place the prepared extremely thin-walled metal pipe on the lower mold plate, and clamp the upper sides of the two ends of the extremely thin-walled metal pipe with the two first clamps respectively, and clamp the lower sides of the two ends of the extremely thin-walled metal pipe with the two second clamps respectively;

[0022] Step S3. Close the mold, the upper mold plate runs downward, and after the upper mold plate contacts the extremely thin-walled metal pipe, continue to run downward, the downward speed of the upper mold plate is controlled at 1-5 mm / min, until the extremely thin-walled metal pipe is in contact with the end face profile of the upper mold plate and the lower mold plate; continue to run downward, the downward speed is controlled at 0.1-1 mm / min, until the extremely thin-walled metal pipe is bent and formed; stop running downward, and keep the mold closed for 10-60 seconds;

[0023] S4. Open the mold, take out the thin-walled metal pipe, take out the polyurethane mandrel from the thin-walled metal pipe, and obtain the bent thin-walled metal pipe.

[0024] Preferably, in step S1, a half-open slot is formed in the middle of each end of the thin-walled metal pipe along the axial direction of the thin-walled metal pipe, the half-open slot separates the end of the thin-walled metal pipe into an upper first clamp holding part and a lower second clamp holding part, and a thin-walled metal pipe to be bent is obtained.

[0025] Preferably, in step S2, two first clamps are respectively clamped to the upper first clamp holding part of each end of the thin-walled metal pipe, and two second clamps are respectively clamped to the lower second clamp holding part of each end of the thin-walled metal pipe; the first clamps and the second clamps are respectively abutted against the two ends of the polyurethane mandrel.

[0026] A method for bending and forming a thin-walled metal pipe, comprising the steps of: during the bending and forming of the thin-walled metal pipe, respectively applying an outward pulling force to the upper side of each end of the thin-walled metal pipe; simultaneously, respectively applying an inward pushing force to the lower side of each end of the thin-walled metal pipe; and respectively forming a half-open slot between the upper side and the lower side of each end of the thin-walled metal pipe.

[0027] The present application provides a thin-walled metal pipe bending and forming device and method, which is particularly suitable for manufacturing thin-walled bent pipes with small relative bending radius and small bending angle using the bending process. The thin-walled metal pipe is formed under the cooperation of the rigid upper and lower molds and the pressure. During the bending and forming process of the thin-walled metal pipe, the pulling clamping device applies an outward pulling force to the inner side of the metal pipe, and the pushing clamping device applies an inward pressure to the outer side of the metal pipe. This solves the technical problems of wrinkles on the inner side and excessive thinning on the outer side of the existing thin-walled metal pipe during the bending and forming process, thereby controlling the displacement of the inner and outer materials of the pipe, and achieving the technical effects of eliminating wrinkles on the inner side and improving the external thinning. At the same time, due to the use of the bending forming process, compared with other metal thin-walled pipe bending forming processes, the present application has the advantages of high production efficiency and low manufacturing cost. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application.

[0029] Figure 1 is a structural schematic diagram (state of clamping a thin-walled metal pipe) of the present application;

[0030] Figure 2 is Figure 1A schematic diagram of the enlarged view of the traction clamping device (fixed clamp holding an extremely thin-walled metal tube);

[0031] Figure 3 for Figure 2 A structural schematic diagram of the enlarged left view of the first clamp (located on the right side);

[0032] Figure 4 for Figure 1 A schematic diagram of the enlarged top-pushing clamping device (fixed clamp holding an extremely thin-walled metal tube);

[0033] Figure 5 for Figure 4 A structural schematic diagram of the enlarged left view of the second clamp (located on the right side);

[0034] Figure 6 for Figure 1 A structural schematic diagram of the enlarged right view of the lower mold (located on the right side);

[0035] Figure 7 for Figure 1 A structural schematic diagram of an enlarged top view of the lower mold (located on the right);

[0036] Figure 8 This is a schematic diagram illustrating the working principle of the ultra-thin-walled metal tube bending process of the present invention; the arrows represent the direction of force.

[0037] Figure 9 This is a schematic diagram of a type of ultra-thin-walled metal tube (with a polyurethane core inserted inside);

[0038] Figure 10 for Figure 9 The diagram shows a structure formed by bending an extremely thin-walled metal tube.

[0039] Figure 11 for Figure 9 A structural schematic diagram of an enlarged view of the left view of the shown view;

[0040] Figure 12 This is a stress distribution diagram of the ultra-thin-walled metal tube described in Example 3;

[0041] Figure 13 This is a diagram showing the stress distribution of the ultra-thin-walled metal tube without a semi-open groove in Example 3.

[0042] Figure 14 A schematic diagram of a first or second clamp with a different structure (connected to the first connecting rod);

[0043] Figure 15 for Figure 14 A structural schematic diagram of the right view of the shown view;

[0044] Figure 16 Fig. 1 is a schematic structural diagram of a pulling clamping device (fixedly clamping a thin-walled metal pipe); Figure 14 Fig. 2 is a schematic structural diagram of a top view of the view shown in Fig. 1;

[0045] Figure 17 Fig. 3 is a schematic structural diagram of another form of a pulling clamping device (fixedly clamping a thin-walled metal pipe);

[0046] Figure 18 Fig. 4 is a schematic structural diagram of another form of a pushing clamping device (fixedly clamping a thin-walled metal pipe).

[0047] Marked in the figure: 1. upper die plate; 2. lower die plate; 3. pulling clamping device; 4. pushing clamping device; 5. thin-walled metal pipe; 6. polyurethane mandrel; 21. arc-shaped straight-through slot; 22. hinged pivot; 23. connecting rod; 24. limiting spring; 25. limiting groove; 31. first clamp; 32. first connecting rod assembly; 33. first support frame; 41. second clamp; 42. second connecting rod assembly; 43. second support frame; 51. half-open slot; 52. first clamp clamping part; 53. second clamp clamping part; 311. first half-annular through slot; 312. outer half-circle snap ring; 313. inner half-circle snap ring; 314. first connecting part; 315. second connecting part; 316. screw; 317. half-annular slot; 321. first connecting rod; 322. second connecting rod; 323. first air cylinder; 324. first telescopic rod; 411. second half-annular through slot; 421. third connecting rod; 422. fourth connecting rod; 423. second air cylinder; 424. second telescopic rod;

[0048] O1 is the hinged point between the first connecting rod assembly 32 and the first support frame 33; O2 is the hinged point between the first clamp 31 and the first connecting rod assembly 32; P1 is the hinged point between the second connecting rod assembly 42 and the second support frame 43; P2 is the hinged point between the second clamp 41 and the second connecting rod assembly 42;

[0049] R1 is the length of the second connecting rod 322; r1 is the sum of the length of the first connecting rod 321 and the first clamp 31; t1 is the length of the overlapping part of the first clamp 31 and the thin-walled metal pipe 5;

[0050] R2 is the length of the fourth connecting rod 422; r2 is the sum of the length of the third connecting rod 421 and the second clamp 41; t2 is the length of the overlapping part of the second clamp 41 and the thin-walled metal pipe 5;

[0051] R3 is the central radius of the first half-annular through slot 311 of the first clamp 31; R4 is the central radius of the second half-annular through slot 411 of the second clamp 41;

[0052] d1 is the width of the first half annular through slot 311 of the first clamp 31; d2 is the width of the second half annular through slot 411 of the second clamp 41;

[0053] α is the angle of the first half annular through slot 311 of the first clamp 31; β is the angle of the second half annular through slot 411 of the second clamp 41; γ is the bending angle of the ultra-thin wall metal pipe 5. DETAILED DESCRIPTION

[0054] In order to make the technical problems, technical solutions and beneficial effects of the present application clearer, the present application will be further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and not to limit the present application. The methods used in the present application are conventional methods unless otherwise specified; the raw materials and devices used are conventional commercially available products unless otherwise specified.

[0055] Example 1

[0056] As shown in Figure 1 The present application provides an ultra-thin wall metal pipe bending forming device, which is provided with an upper die mechanism and a lower die mechanism, the upper die mechanism is provided with an upper die plate 1, the lower die mechanism is provided with a lower die plate 2, the lower die plate 2 is spaced below the upper die plate 1, and the die cavity of the upper die mechanism and the lower die mechanism in the closed die state is adapted to the metal pipe after bending forming.

[0057] The bending forming device is also provided with a pair of pulling clamping mechanisms and a pair of pushing clamping mechanisms, the pulling clamping mechanisms are spaced above the pushing clamping mechanisms, wherein:

[0058] The pulling clamping mechanism is provided with a pair of pulling clamping devices 3, which are respectively arranged on the left and right sides of the upper die plate 1 and the lower die plate 2; the pulling clamping device 3 is provided with a first clamp 31, a first connecting rod assembly 32 and a first support frame 33, the first clamp 31 is hingedly connected with the first connecting rod assembly 32, and the first connecting rod assembly 32 is hingedly connected with the first support frame 33; the initial state of the first connecting rod assembly 32 is straightened state.

[0059] The pushing clamping mechanism is provided with a pair of pushing clamping devices 4, which are respectively arranged on the left and right sides of the upper die plate 1 and the lower die plate 2; the pushing clamping device 4 is provided with a second clamp 41, a second connecting rod assembly 42 and a second support frame 43, the second clamp 41 is hingedly connected with the second connecting rod assembly 42, and the second connecting rod assembly 42 is hingedly connected with the second support frame 43; the initial state of the second connecting rod assembly 42 is bent state.

[0060] The lower die mechanism is provided with a pair of lower die plates 2, the pair of lower die plates 2 are spaced left and right and symmetrically arranged relative to the upper die plate 1; the lower die plate 2 is provided with an arc-shaped straight through slot 21 (such as Figure 6 ,Figure 7 The arc-shaped straight-through groove 21 is used for limiting the thin-walled metal pipe 5. The bottom of the lower die plate 2 is provided with a hinged rotating shaft 22, and the outer side of the lower die plate 2 is fixedly connected with a connecting rod 23 connected with a limiting spring 24.

[0061] The first clamps 31 and the second clamps 41 are prior art and are used for fixing the two ends of the thin-walled metal pipe 5. The two first clamps 31 are used for clamping the upper sides of the two ends of the thin-walled metal pipe 5, and the two second clamps 41 are used for clamping the lower sides of the two ends of the thin-walled metal pipe 5.

[0062] The first connecting rod assembly 32 and the second connecting rod assembly 42 are prior art. The first connecting rod assembly 32 is in a straight state, and the second connecting rod assembly 42 is in a bent state. Through the relative rotation between the connecting rods of the first connecting rod assembly 32 and the second connecting rod assembly 42 (the power comes from the bending of the thin-walled metal pipe 5), the two ends of the thin-walled metal pipe 5 are respectively pulled outward by the pulling clamping mechanism, and the lower sides of the two ends of the thin-walled metal pipe 5 are respectively pressed inward by the pushing clamping mechanism.

[0063] As shown in Figure 2 The initial state of the first connecting rod assembly 32 is a straight state. When in the initial undeformed state, the distance between the first clamp 31 and the hinge point O1 between the first connecting rod assembly 32 and the first support frame 33 is the farthest. When the thin-walled metal pipe 5 starts to be pressed down under the action of the upper die plate 1, the first connecting rod assembly 32 rotates around the hinge point O1 and the hinge point O2 between the first clamp 31 and the first connecting rod assembly 32, so that the distance between the first clamp 31 and the hinge point O1 decreases. At this time, the first clamp 31 generates an outward pulling force on the thin-walled metal pipe 5.

[0064] As shown in Figure 4 The initial state of the second connecting rod assembly 42 is a bent state. When in the initial undeformed state, the distance between the second clamp 41 and the hinge point P1 between the second connecting rod assembly 42 and the second support frame 43 is the closest. When the thin-walled metal pipe 5 starts to be pressed down under the action of the upper die plate 1, the second clamp 41 rotates around the hinge point P1 and the hinge point P2 between the second clamp 41 and the second connecting rod assembly 42, so that the distance between the second clamp 41 and the hinge point P1 increases. At this time, the second clamp 41 generates an inward pushing force on the thin-walled metal pipe 5.

[0065] As shown in Figure 1 , Figure 8As shown, in use, after the mold is opened, the prepared thin-walled metal pipe 5 is placed in the arc-shaped straight grooves 21 of the pair of lower mold plates 2, the two first clamps 31 are respectively clamped on the upper sides of the two ends of the thin-walled metal pipe 5, and the two second clamps 41 are respectively clamped on the lower sides of the two ends of the thin-walled metal pipe 5. Then the mold is closed, the upper mold plate 1 is pressed down, the thin-walled metal pipe 5 is gradually bent downward, and the lower mold plate 2 is further pushed to rotate around the hinge shaft 22, so that the gap between the two lower mold plates 2 becomes larger, and the middle part of the thin-walled metal pipe 5 is bent downward. In this process, the two lower mold plates 2 cooperatively guide, limit and position the bending of the thin-walled metal pipe 5, and finally the thin-walled metal pipe 5 is bent into a V-shaped structure. During the pressing process of the upper mold plate 1, on the one hand, the initial state of the first connecting rod assembly 32 of the pulling clamping device 3 is straight, the first clamp 31 rotates relative to the first connecting rod assembly 32, the first connecting rod assembly 32 rotates relative to the first support frame 33, and the inner side of the thin-walled metal pipe 5 is subjected to the action of the first clamp 31, that is, the upper sides of the two ends of the thin-walled metal pipe 5 are respectively subjected to the pulling force to the two ends (i.e. outward), so as to eliminate the wrinkles on the inner side of the thin-walled metal pipe 5; on the other hand, the initial state of the second connecting rod assembly 42 of the pushing clamping device 4 is bent, the second clamp 41 rotates relative to the second connecting rod assembly 42, the second connecting rod assembly 42 rotates relative to the second support frame 43, and the outer side of the thin-walled metal pipe 5 is subjected to the action of the second clamp 41, that is, the lower sides of the two ends of the thin-walled metal pipe 5 are respectively subjected to the pushing force inward, so as to thin the outer side of the thin-walled metal pipe 5 and improve the thinning, realize the partition control, and especially suitable for manufacturing thin-walled metal pipe 5 with small relative bending radius.

[0066] The first connecting rod assembly 32 of the pulling clamping device 3 can be a prior art, or can have the following structure: Figure 2 As shown, the first connecting rod assembly 32 is provided with a first connecting rod 321 and a second connecting rod 322; one end of the first connecting rod 321 is hingedly connected with the first clamp 31, the other end of the first connecting rod 321 is hingedly connected with one end of the second connecting rod 322, and the other end of the second connecting rod 322 is hingedly connected with the first support frame 33; the included angle between the first connecting rod 321 and the second connecting rod 322 is initially 180°, so that the initial state of the first connecting rod assembly 32 is straight.

[0067] In order to adapt the bending and forming of the thin-walled metal pipe 5 with different hole diameters, the hinge shaft 22 of the lower mold plate 2 can be provided with a plurality of hinge shafts 22 with different diameters, and the hinge shafts 22 with different diameters are respectively matched with the thin-walled metal pipe 5 with different hole diameters. Figure 2As shown, the first support frame 33 of the present invention is preferably a telescopic rod with an existing locking structure, and the extension rod of the first support frame 33 is hinged to the first connecting rod assembly 32. The extension rod of the first support frame 33 can be lengthened or shortened according to the diameter of the ultra-thin-walled metal tube 5, so that the first connecting rod assembly 32 is kept in a horizontal state, and the first clamp 31 clamps the upper sides of the two ends of the ultra-thin-walled metal tube 5.

[0068] The first clamp 31 of the traction clamping device 3 can be based on existing technology, or it can have the following structure: composed of... Figure 3 As shown, the first clamp 31 has a first semi-annular through groove 311 for inserting and fixing the upper side of the end of the ultra-thin-walled metal tube 5, making loading and unloading convenient and quick; the fixing method usually uses screws through the matching threads on the first clamp 31 to press and fix the upper side of the end of the ultra-thin-walled metal tube 5 against the first semi-annular through groove 311.

[0069] The second link assembly 42 of the push-clamping device 4 can be based on existing technology, or it can have the following structure: composed of... Figure 4 As shown, the second link assembly 42 is provided with a third link 421 and a fourth link 422; one end of the third link 421 is hinged to the second clamp 41, the other end of the third link 421 is hinged to one end of the fourth link 422, and the other end of the fourth link 422 is hinged to the second support frame 43; the included angle between the third link 421 and the fourth link 422 is not equal to 180° in the initial state, so that the initial state of the second link assembly 42 is a bent state.

[0070] This invention allows for relatively convenient determination of the dimensions of the relevant components of the aforementioned pulling and clamping device 3 and pushing and clamping device 4. Preferably, under ideal conditions, the following empirical formula can also be used, and adjustments can be made according to actual circumstances.

[0071] (1) Point of application of tension: The tension clamping device 3 is provided with a first clamp 31, a first connecting rod assembly 32, and a first support frame 33. In the case where the first connecting rod assembly 32 is provided with a first connecting rod 321 and a second connecting rod 322, the empirical formula is as follows:

[0072]

[0073] In the formula, R1 is the length of the second connecting rod 322; r1 is the sum of the lengths of the first connecting rod 321 and the first clamp 31; t1 is the length of the overlapping portion of the first clamp 31 and the ultra-thin-walled metal tube 5; D is the outer diameter of the ultra-thin-walled metal tube 5; ΔL is half of the change in the axial length of the inner side of the ultra-thin-walled metal tube 5; from Figure 2 As shown. Once the above dimensions are determined, the relevant dimensions of the first support frame 33 can be determined accordingly based on the actual situation.

[0074] Since t1 is the length of the overlapping portion between the first clamp 31 and the ultra-thin-walled metal tube 5, it is assumed that the ultra-thin-walled metal tube 5 at position t1 does not undergo axial deformation. Let L be half the length of the ultra-thin-walled metal tube 5. Then, theoretically, the average axial deformation rate of the ultra-thin-walled metal tube 5 is ΔL / (Lt). Since the wrinkling defects on the inner side of the ultra-thin-walled metal tube 5 are greatly affected by the change in its axial length, it needs to be taken into account in the empirical formula for tensile force.

[0075] When the ultra-thin-walled metal tube 5 is bent, its inner axial length will shorten, thus increasing its tendency to wrinkle. Combining the principle of constant volume and the assumption of plane strain, it is possible to roughly estimate whether wrinkling will occur on the inner side of the tube, and to determine the ΔL required to avoid wrinkling on the inner side of a given tube.

[0076] (2) Point of application of thrust: The push clamping device 4 is provided with a second clamp 41, a second connecting rod assembly 42, and a second support frame 43. In the case where the second connecting rod assembly 42 is provided with a third connecting rod 421 and a fourth connecting rod 422, the empirical formula is as follows:

[0077]

[0078] In the formula, R2 is the length of the fourth link 422; r2 is the sum of the lengths of the third link 421 and the second clamp 41; t2 is the length of the overlapping portion of the second clamp 41 and the ultra-thin-walled metal tube 5, derived from... Figure 4 As shown. Once the dimensions of these three components are determined, the relevant dimensions of the second support frame 43 can be determined accordingly based on the actual situation.

[0079] To enable the present invention to adapt to the bending and forming of extremely thin-walled metal tubes 5 with different apertures, by Figure 4 As shown, the second support frame 43 is a telescopic rod with a locking structure, and the extension rod of the second support frame 43 is hinged to the second connecting rod assembly 42.

[0080] The second clamp 41 of the push-grip device 4 can be based on existing technology, or it can have the following structure: (The structure consists of...) Figure 5 As shown, the second clamp 41 has a second semi-annular through groove 411 for inserting and fixing the lower side of the end of the ultra-thin-walled metal tube 5, making loading and unloading convenient and quick; the fixing method usually uses screws through the matching threads on the second clamp 41 to press and fix the lower side of the end of the ultra-thin-walled metal tube 5 against the second semi-annular through groove 411.

[0081] Depend on Figure 6 , Figure 7As shown, a limiting groove 25 is preferably provided on the outer side of the bottom of the arc-shaped straight groove 21. When it is possible to clamp the lower end of the ultra-thin-walled metal tube 5 with the second clamp 41, if the relative position between the second clamp 41 and the lower template 2 is interfered and cannot be achieved, the head of the second clamp 41 can be inserted into the limiting groove 25. By partially interleaving the positions between the second clamp 41 and the lower template 2, the second clamp 41 can clamp the lower end of the ultra-thin-walled metal tube 5.

[0082] Example 2

[0083] like Figure 1 As shown, the present invention provides a method for bending and forming an ultra-thin-walled metal tube, using the ultra-thin-walled metal tube bending and forming apparatus described in Embodiment 1 above, comprising the following steps:

[0084] S1. Obtain the ultra-thin-walled metal tube 5 that needs to be bent, and insert the polyurethane core rod 6 into the ultra-thin-walled metal tube 5 to prepare for the bending and forming of the ultra-thin-walled metal tube 5.

[0085] S2. Open the mold, place the prepared ultra-thin wall metal tube 5 on the lower template 2, clamp the upper sides of the two ends of the ultra-thin wall metal tube 5 with the two first clamps 31 respectively, and clamp the lower sides of the two ends of the ultra-thin wall metal tube 5 with the two second clamps 41 respectively.

[0086] S3. Mold closing: The upper mold plate 1 moves downwards. After the upper mold plate 1 contacts the ultra-thin-walled metal tube 5, it continues to move downwards. The downward speed of the upper mold plate 1 is controlled at 1-5 mm / min until the end face contours of the ultra-thin-walled metal tube 5 are aligned with the mold. The upper mold plate 1 continues to move downwards, with the downward speed controlled at 0.1-1 mm / min, until the ultra-thin-walled metal tube 5 is bent and formed. The upper mold plate 1 stops moving downwards, and the mold is closed and pressure is maintained for 10-60 seconds. During this process, the ultra-thin-walled metal tube 5 deforms under pressure, and the internal polyurethane core rod 6 provides support for the tube, alleviating the wrinkling phenomenon on the inner side of the ultra-thin-walled metal tube 5. Meanwhile, the external force mechanism adjusts the displacement, that is, the tension clamping mechanism applies an outward tension to the inner side of both ends of the ultra-thin-walled metal tube 5, and the push clamping mechanism applies an inward push to the outer side of both ends of the ultra-thin-walled metal tube 5. The implementation of the above tension and push forces forms zoned stress on the inner and outer sides of both ends of the ultra-thin-walled metal tube 5, thereby suppressing wrinkling on the inner side of the tube, improving the thinning on the outer side, and increasing the forming limit of the tube in the bending process.

[0087] S4. Open the mold, take out the thin-walled metal pipe 5, take out the polyurethane core rod 6 from the thin-walled metal pipe 5, and obtain the bent thin-walled metal pipe 5. Specifically, the upper mold plate 1 is driven to move upward by the press at a speed of 5-10 mm / s, and the formed part is wrapped in the lower mold plate 2 due to the hard friction between the thin-walled metal pipe 5 and the lower mold plate 2, so that the bent thin-walled metal pipe 5 is easily taken out from the lower mold plate 2 to obtain the final formed part.

[0088] Example 3

[0089] The present application adopts the thin-walled metal pipe bending forming method of example 2, and uses the thin-walled metal pipe bending forming device of example 1, and the specific structure and its effect are described in example 1, which will not be repeated here. The steps include:

[0090] S1. Take the thin-walled metal pipe 5 with a wall thickness of 1 mm, an outer diameter of 50 mm, and a pipe length of 200 mm, and the metal material is selected from 6061 aluminum alloy suitable for electronics and aviation. Along the axial direction of the thin-walled metal pipe 5, a half-open slot 51 with a width of 20 mm and a depth of 50 mm is formed at a height of half of the outer diameter of the thin-walled metal pipe 5 at both ends, and the half-open slot 51 is a 90-degree tapered slot. The half-open slot 51 separates the upper and lower parts of the end of the thin-walled metal pipe 5 into a first clamp clamping part 52 and a second clamp clamping part 53, and obtains the thin-walled metal pipe 5 that needs to be bent. Take the polyurethane core rod 6 with a hardness of 100, a diameter of 48 mm, and a length of 180 mm, and insert it into the thin-walled metal pipe 5 to prepare for the bending forming of the thin-walled metal pipe 5, as shown in Figure 9 .

[0091] S2. Open the mold, place the prepared thin-walled metal pipe 5 in the arc-shaped straight slot 21 of the lower mold plate 2, clamp the first clamp clamping part 52 on the upper side of the two ends of the thin-walled metal pipe 5 with two first clamps 31 respectively, and clamp the second clamp clamping part 53 on the lower side of the two ends of the thin-walled metal pipe 5 with two second clamps 41 respectively; at the same time, the first clamp 31 and the second clamp 41 abut against the two ends of the polyurethane core rod 6 respectively, and the polyurethane core rod 6 is positioned. Among them:

[0092] As shown in Figure 2 , the first connecting rod 321 and the second connecting rod 322 of the first connecting rod assembly 32 are both rectangular plates with a thickness of 5 mm, a length of 160 mm, and two ends of circular arc shape with a diameter of 5 mm hole. As shown in Figure 4 , the third connecting rod 421 and the fourth connecting rod 422 of the second connecting rod assembly 42 are the same as the first connecting rod 321 and the second connecting rod 322 except that the length is 50 mm, which will not be repeated here.

[0093] As shown in Figure 3 ,Figure 5 As shown, the first clamp 31 and the second clamp 41 are respectively connected with the pipe material with a center radius of 25 mm, and a 1 / 4 circular arc-shaped clamp die with a 1 mm wide groove, that is, the center radius R3 and R4 of the first half-ring-shaped through groove 311 and the second half-ring-shaped through groove 411 are both 25 mm, the width d1 and d2 are both 1 mm, and the angle α and β of the circular arc are both 90°.

[0094] S3. Clamping, the upper die plate 1 runs downward, after the upper die plate 1 contacts the extremely thin-walled metal pipe 5, the upper die plate 1 continues to run downward at a speed controlled at 1-5 mm / min, until the end surface profile of the extremely thin-walled metal pipe 5 is attached to the upper die plate 1 and the lower die plate 2; the upper die plate 1 continues to run downward at a speed controlled at 0.1-1 mm / min, until the extremely thin-walled metal pipe 5 is bent and formed, the distance of the downward running of the upper die plate 1 is half of the length of the extremely thin-walled metal pipe 5, that is, 100 mm; the upper die plate 1 stops running downward, clamping and pressure maintaining for 10-60 s, and finally the bent and formed extremely thin-walled metal pipe 5 is obtained, the bending angle γ of the extremely thin-walled metal pipe 5 is about 90°, as shown in Figure 10 .

[0095] S4. Unclamping, the upper die plate 1 runs upward at a speed of 5-10 mm / s, the extremely thin-walled metal pipe 5 is taken out, the polyurethane core rod 6 is taken out from the extremely thin-walled metal pipe 5, and the bent extremely thin-walled metal pipe 5 is obtained.

[0096] Figure 12 the stress distribution state diagram of the extremely thin-walled metal pipe 5 described in Example 3; Figure 13 the stress distribution state diagram of the extremely thin-walled metal pipe 5 without the half-opened groove 51 for comparison. As can be seen from Figure 13 when external force is applied, if the half-opened groove 51 is not provided, the pulling force applied by the pulling clamping device 3 arranged on the upper side (that is, the inner side) and the pushing force applied by the pushing clamping device 4 arranged on the lower side (that is, the outer side) are intertwined, and affect each other, thereby causing the wrinkles on the inner side of the bent and formed extremely thin-walled metal pipe 5 to be intensified.

[0097] As can be seen from Figure 12 when external force is applied, although the inner side pulling force applied by the pulling clamping device 3 and the outer side pushing force applied by the pushing clamping device 4 converge at the bottom of the slot of the half-opened groove 51, due to the provision of the half-opened groove 51, the transmission of the inner side pulling force to the outer side and the transmission of the outer side pushing force to the outer side are inhibited, and the bending and forming effect of the extremely thin-walled metal pipe 5 is better.

[0098] Therefore, the present application provides a kind of extremely thin-walled metal tube bending forming method, in the existing extremely thin-walled metal tube 5 bending forming process, respectively to the upper side of the two end portions of extremely thin-walled metal tube 5 Outwardly applied pulling force, thereby eliminating the wrinkling of the tube body (i.e. inside) of the upper side of the extremely thin-walled metal tube 5;At the same time, respectively to the lower side of the two end portions of extremely thin-walled metal tube 5 Inwardly applied pushing force, thereby improving the excessive thinning of the tube body (i.e. outside) of the lower side of the extremely thin-walled metal tube 5, finally realizes the partition control, that is, it can solve the technical problems of wrinkling inside and excessive thinning outside of the existing extremely thin-walled bent pipe.

[0099] Preferably, a half-open slot 51 is formed between the upper side and the lower side of the two end portions of the extremely thin-walled metal tube 5, which maximizes the mutual entanglement and influence between the outward pulling force applied to the upper side of the two end portions and the inward pushing force applied to the lower side, and inhibits the entanglement and interference between the two, thereby further improving the bending forming effect of the extremely thin-walled metal tube 5.

[0100] Example 4

[0101] The first clamp 31 of the pushing and clamping device 4 described in the embodiment 3 of the present application can also have the following structure in addition to the above structure:

[0102] As shown in Figure 14- Figure 16 , the first clamp 31 of another structure of the present application is provided with an outer semicircular snap ring 312 and an inner semicircular snap ring 313, the two ends of the outer semicircular snap ring 312 respectively extend outwardly to form a first connecting portion 314, and the two ends of the inner semicircular snap ring 313 respectively extend outwardly to form a second connecting portion 315;The outer semicircular snap ring 312 and the inner semicircular snap ring 313 face the same direction and are arranged in a superposed manner, the first connecting portion 314 of the outer semicircular snap ring 312 and the second connecting portion 315 of the inner semicircular snap ring 313 are detachably connected (usually by screws 316), and a semicircular groove 317 is formed between the outer semicircular snap ring 312 and the inner semicircular snap ring 313. The outer semicircular snap ring 312 of the first clamp 31 is hingedly connected to the first connecting rod 321.

[0103] In use, the outer semicircular snap ring 312 is tightly attached to the outer wall of the upper side of the end portion of the extremely thin-walled metal tube 5, the inner semicircular snap ring 313 is tightly attached to the inner wall of the upper side of the end portion of the extremely thin-walled metal tube 5, and the second connecting portion 315 extends out of the half-open slot 51, the first connecting portion 314 and the second connecting portion 315 on the same side are fixed by screws 316, and the upper side of the end portion of the extremely thin-walled metal tube 5 is fixed in the semicircular groove 317 by the pressing force.

[0104] The second clamp 41 of another structure of the present application is the same as the first clamp 31 of another structure described in the present embodiment, which will not be repeated here.

[0105] Example 5

[0106] In addition to the above-described structures, the traction clamping device 3 and the push clamping device 4 of the present invention can also adopt the following structures:

[0107] Depend on Figure 17 As shown, the first connecting rod 321 of the first connecting rod assembly 32 described in Embodiment 1 is replaced with a first cylinder 323, and the second connecting rod 322 is replaced with a first telescopic rod 324 equipped with an existing locking structure. That is, the first connecting rod assembly 32 is provided with a first cylinder 323 and a first telescopic rod 324 with a locking structure. The piston rod of the first cylinder 323 is hinged to the first clamp 31, the cylinder body of the first cylinder 323 is hinged to the telescopic rod end of the first telescopic rod 324, and the tail rod of the first telescopic rod 324 is hinged to the first support frame 33. The initial angle between the first cylinder 323 and the first telescopic rod 324 is 180°. The other structures, connections, and working principles of the first connecting rod assembly 32 in this embodiment are the same as those in Embodiment 1, and will not be repeated here.

[0108] Depend on Figure 18 As shown, the third link 421 of the second link assembly 42 described in Embodiment 1 is replaced with the second cylinder 423, and the fourth link 422 is replaced with the second telescopic rod 424 equipped with an existing locking structure. That is, the second link assembly has a second cylinder 423 and a second telescopic rod 424. The piston rod of the second cylinder 423 is hinged to the second clamp 41, the cylinder body of the second cylinder 423 is hinged to the telescopic rod end of the second telescopic rod 424, and the tail rod of the second telescopic rod 424 is hinged to the second support frame 43. The initial angle between the second cylinder 423 and the second telescopic rod 424 is not equal to 180°. The other structures, connections, and working principles of the second link assembly 42 in this embodiment are the same as those in Embodiment 1, and will not be repeated here.

[0109] In use, the lengths of the first connecting rod 321 and the second connecting rod 322 are adjusted by adjusting the piston rod length of the first cylinder 323 and the telescopic rod length of the first telescopic rod 324, respectively. Similarly, the lengths of the third connecting rod 421 and the fourth connecting rod 422 are adjusted by adjusting the piston rod length of the second cylinder 423 and the telescopic rod length of the second telescopic rod 424, thereby satisfying the bending forming of different ultra-thin-walled metal tubes 5. Furthermore, the tension and thrust on the ultra-thin-walled metal tube 5 can be adjusted by operating the first cylinder 323 and the second cylinder 423 respectively during bending.

[0110] It should be noted that:

[0111] (1) The material of the ultra-thin wall metal tube 5 can be 6061 aluminum alloy or other existing metal materials.

[0112] (2) The hardness of the polyurethane mandrel 6 can be 100, or other hardness according to actual situation, preferably higher hardness, so that the thin-walled metal pipe 5 is less deformed when bending.

[0113] (3) Considering the rebound in practice, the distance (i.e. the pressing amount) that the upper die plate 1 continues to run downward after the end surface profile of the thin-walled metal pipe 5 is attached to the upper die plate 1 and the lower die plate 2 in the step S3 is larger than the theoretical distance, for example, the distance that the upper die plate 1 runs downward in the step S3 in the embodiment 3 can be adjusted from 100 mm to 110 mm according to actual experience.

[0114] (4) The half-open slot 51 can be a 90-degree tapered slot, or other shape according to actual situation.

[0115] (5) The first clamp 31 and the second clamp 41 of another structure described in the embodiment 4 can also be used in the embodiment 1, and the outer semicircular clasp ring 312 is hingedly connected to the first connecting rod assembly 32.

[0116] In the description of the present application, it should be understood that the terms "left", "right", "up", "down", "top", "bottom", "front", "back", "inner", "outer", "back", "middle" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application and simplify the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. It should be noted that in the above embodiments, "first", "second", "third" and "fourth" do not represent absolute division of structure and / or function, nor represent the execution order, but only for the convenience of description.

[0117] The above is only the preferred embodiment of the present application, and does not limit the present application, any modification, equivalent replacement and improvement made within the spirit and principle of the present application, for example, the present application can not only be applied to the press bending forming of the thin-walled metal pipe 5, but also can be applied to the press bending forming of the thin-walled metal pipe according to actual situation; the structure of the second clamp 41 is the same as that of the first clamp 31, etc., which should be included in the protection scope of the present application.

Claims

1. An ultra-thin-walled metal tube press bending forming device, the press bending forming device is provided with an upper die mechanism and a lower die mechanism, the upper die mechanism is provided with an upper die plate (1), the lower die mechanism is provided with a lower die plate (2), the lower die plate (2) is spaced below the upper die plate (1), and the die cavity of the upper die mechanism and the lower die mechanism in the closed die state is adapted to the metal tube after bending forming; characterized in that, the press bending forming device is also provided with a pair of pulling clamping mechanisms and a pair of pushing clamping mechanisms, the pulling clamping mechanisms are spaced above the pushing clamping mechanisms; while the outward pulling force is applied to the inner side of the metal tube by the pulling clamping devices, the inward pressure is applied to the outer side of the metal tube by the pushing clamping devices; the pulling clamping mechanisms are provided with a pair of pulling clamping devices (3) which are respectively arranged on the left and right sides of the upper die plate (1) and the lower die plate (2); the pulling clamping device (3) is provided with a first clamp (31), a first connecting rod assembly (32) and a first support frame (33), the first clamp (31) is hingedly connected with the first connecting rod assembly (32), and the first connecting rod assembly (32) is hingedly connected with the first support frame (33); the initial state of the first connecting rod assembly (32) is straightened state; the pushing clamping mechanisms are provided with a pair of pushing clamping devices (4) which are respectively arranged on the left and right sides of the upper die plate (1) and the lower die plate (2); the pushing clamping device (4) is provided with a second clamp (41), a second connecting rod assembly (42) and a second support frame (43), the second clamp (41) is hingedly connected with the second connecting rod assembly (42), and the second connecting rod assembly (42) is hingedly connected with the second support frame (43); the initial state of the second connecting rod assembly (42) is bent state; the lower die mechanism is provided with a pair of lower die plates (2), the pair of lower die plates (2) are spaced left and right and symmetrically arranged relative to the upper die plate (1); the lower die plate (2) is provided with an upwardly open arc-shaped straight-through groove (21) for limiting the ultra-thin-walled metal tube (5); the bottom of the lower die plate (2) is provided with a hinged rotating shaft (22), and the outer side of the lower die plate (2) is fixedly connected with a connecting rod (23), and the connecting rod (23) is connected with a limiting spring (24); the first connecting rod assembly (32) is provided with a first cylinder (323) and a first telescopic rod (324) with a locking structure; the piston rod of the first cylinder (323) is hingedly connected with the first clamp (31), the cylinder body of the first cylinder (323) is hingedly connected with the telescopic rod end of the first telescopic rod (324), the tail rod of the first telescopic rod (324) is hingedly connected with the first support frame (33), and the included angle between the first cylinder (323) and the first telescopic rod (324) is initially 180°. The second linkage assembly is provided with a second cylinder (423) and a second telescopic rod (424), a piston rod of the second cylinder (423) is hingedly connected with the second clamp (41), a cylinder body of the second cylinder (423) is hingedly connected with a telescopic rod end of the second telescopic rod (424), a tail rod of the second telescopic rod (424) is hingedly connected with the second support frame (43), and an included angle between the second cylinder (423) and the second telescopic rod (424) is not equal to 180° in an initial state.

2. The apparatus for press bending forming of an extremely thin-walled metal pipe according to claim 1, wherein The first linkage assembly (32) is provided with a first linkage (321) and a second linkage (322); one end of the first linkage (321) is hingedly connected with the first clamp (31), the other end of the first linkage (321) is hingedly connected with one end of the second linkage (322), and the other end of the second linkage (322) is hingedly connected with the first support frame (33); and an included angle between the first linkage (321) and the second linkage (322) is 180° in an initial state.

3. The apparatus according to claim 1, wherein The first clamp (31) is provided with an outer semicircular clasp ring (312) and an inner semicircular clasp ring (313), both ends of the outer semicircular clasp ring (312) are respectively outwardly extended to be provided with first connecting portions (314), both ends of the inner semicircular clasp ring (313) are respectively outwardly extended to be provided with second connecting portions (315); the outer semicircular clasp ring (312) and the inner semicircular clasp ring (313) are towards the same direction and are arranged in a superposed manner, the first connecting portions (314) and the second connecting portions (315) are detachably connected, and a semicircular groove (317) is formed between the outer semicircular clasp ring (312) and the inner semicircular clasp ring (313); and the outer semicircular clasp ring (312) is hingedly connected with the first linkage assembly (32).

4. The apparatus for press bending forming of an extra thin-walled metal pipe according to claim 1, wherein The second linkage assembly (42) is provided with a third linkage (421) and a fourth linkage (422); one end of the third linkage (421) is hingedly connected with the second clamp (41), the other end of the third linkage (421) is hingedly connected with one end of the fourth linkage (422), and the other end of the fourth linkage (422) is hingedly connected with the second support frame (43); and an included angle between the third linkage (421) and the fourth linkage (422) is not equal to 180° in an initial state.

5. The apparatus for press bending forming of an extra thin-walled metal pipe according to claim 1, wherein The first support frame (33) is a telescopic rod with a locking structure, and an extended rod of the first support frame (33) is hingedly connected with the first linkage assembly (32); and the second support frame (43) is a telescopic rod with a locking structure, and an extended rod of the second support frame (43) is hingedly connected with the second linkage assembly (42).

6. The apparatus for press bending forming of an extra thin-walled metal pipe according to any one of claims 1, 4 and 5, characterized by A first semicircular through groove (311) for inserting and fixing an upper side of an end portion of the extremely thin-walled metal pipe (5) is formed on the first clamp (31); and a second semicircular through groove (411) for inserting and fixing a lower side of an end portion of the extremely thin-walled metal pipe (5) is formed on the second clamp (41).

7. A method of press bending forming of an ultra-thin-walled metal tube, characterized by, The use of the extremely thin-walled metal pipe press-bending forming device according to any one of claims 1-6 comprises the following steps: Step S1. Obtain the ultra-thin-walled metal pipe (5) that needs to be bent, and insert the polyurethane mandrel (6) into the ultra-thin-walled metal pipe (5) to prepare for the bending forming of the ultra-thin-walled metal pipe (5); Step S2. Open the mold, place the prepared ultra-thin-walled metal pipe (5) on the lower mold plate (2), and clamp the upper sides of the two ends of the ultra-thin-walled metal pipe (5) with two first clamps (31) respectively, and clamp the lower sides of the two ends of the ultra-thin-walled metal pipe (5) with two second clamps (41) respectively; Step S3. Close the mold, the upper mold plate (1) runs downward, and after the upper mold plate (1) contacts the ultra-thin-walled metal pipe (5), it continues to run downward, the downward speed of the upper mold plate (1) is controlled at 1-5 mm / min, until the end face profile of the ultra-thin-walled metal pipe (5) is in contact with the upper mold plate (1) and the lower mold plate (2); the upper mold plate (1) continues to run downward, and the downward speed is controlled at 0.1-1 mm / min, until the ultra-thin-walled metal pipe (5) is bent and formed; the upper mold plate (1) stops running downward, and the mold is kept closed for 10-60s; Step S4. Open the mold, take out the ultra-thin-walled metal pipe (5), and take out the polyurethane mandrel (6) from the ultra-thin-walled metal pipe (5), to obtain the bent ultra-thin-walled metal pipe (5).

8. A method of press bending a very thin-walled metal tube according to claim 7, wherein In step S1, a half-open slot (51) is formed in the middle of the two ends of the thin-walled metal pipe (5) along the axial direction of the thin-walled metal pipe (5), which divides the upper and lower ends of the thin-walled metal pipe (5) into a first clamp clamping part (52) and a second clamp clamping part (53), and obtains the ultra-thin-walled metal pipe (5) that needs to be bent; In step S2, the two first clamps (31) clamp the first clamp clamping parts (52) on the upper sides of the two ends of the ultra-thin-walled metal pipe (5) respectively, and the two second clamps (41) clamp the second clamp clamping parts (53) on the lower sides of the two ends of the ultra-thin-walled metal pipe (5) respectively; the first clamps (31) and the second clamps (41) abut against the two ends of the polyurethane mandrel (6) respectively.

9. A method of press bending a very thin-walled metal tube according to claim 7 or 8, characterized in that, It includes the steps of: during the bending forming of the ultra-thin-walled metal pipe (5), respectively applying an outward pulling force to the upper sides of the two ends of the ultra-thin-walled metal pipe (5); at the same time, respectively applying an inward pushing force to the lower sides of the two ends of the ultra-thin-walled metal pipe (5); and respectively opening a half-open slot (51) between the upper sides and the lower sides of the two ends of the ultra-thin-walled metal pipe (5).

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