Thin-wall pipe fitting bending forming device and forming method

Abstract

The invention discloses a thin-wall pipe fitting bending forming device and method, and belongs to the technical field of pipe fitting forming. The thin-wall pipe fitting bending forming device comprises a rack, a lower die is arranged on a workbench of the rack, a plurality of lower forming cavities are formed in the lower die, and an upper die matched with the lower die is arranged above the workbench; a supporting mechanism is arranged on the workbench and comprises a first sliding seat, and supporting units corresponding to the lower forming cavities one to one are arranged on the first sliding seat; a traction mechanism for pulling the pipe blank is arranged on the workbench, the traction mechanism comprises a second sliding seat, and traction units in one-to-one correspondence with the lower forming cavities are arranged on the second sliding seat; the supporting unit and the traction unit are located at the feeding end and the discharging end of the lower forming cavity correspondingly. By means of the thin-wall pipe fitting bending forming device and method, the problems that when an existing forming device conducts bending forming on a thin-wall pipe fitting, the supporting effect is poor, and the pipe fitting forming quality and forming efficiency are affected can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of pipe fitting forming, and particularly relates to a bending forming device and a forming method for thin-walled pipe fittings. Background Art

[0002] Due to characteristics such as light weight and high strength, thin-walled bent pipes are widely used in aerospace equipment. During the integral forming process of thin-walled bent pipes, the outer side of the bent pipe is mainly subjected to tensile stress, and the outer side is thinned due to tensile deformation to form the outer side of the bent pipe. In the process of pipe fitting bending forming, it is extremely easy for the outer side of the bend to be thinned and cracked. During the forming process of the bent pipe, the material on the inner side of the bent pipe is subjected to tangential compressive stress, and the stability of the pipe fitting in the wall thickness direction is relatively poor. When the tangential compressive stress received by the pipe wall exceeds the bearing limit of the pipe fitting, defects such as wrinkling and cross-sectional distortion will occur on the inner side of the bend. These defects such as cracking, wrinkling, and cross-sectional distortion will all affect the quality of the bent pipe and the normal use of the bent pipe.

[0003] In order to reduce the cracking and wrinkling defects of thin-walled pipe fittings during the forming process, elastic blocks are often arranged inside the pipe fittings, and the side wall of the pipe is supported by the elastic blocks to improve the forming quality of the side wall of the pipe fitting. During the bending process of the pipe fitting, it is necessary to heat the pipe fitting to improve the deformation performance of the pipe fitting. However, heating will affect the support strength of the elastic block and weaken the support effect of the elastic block on the pipe fitting.

[0004] The existing patent CN202410202553.9 discloses a push-bending forming device and a forming method thereof. An insulating medium is arranged inside the pipe blank, a filling rubber is arranged inside the insulating medium, and a heating component is arranged outside the bending section. The above patent can reduce the heat transfer from the pipe blank to the filling rubber, so that the filling rubber can still maintain a good hardness during the differential temperature push-bending process, provide good support for the forming of the bent pipe, and improve the forming quality of the bent pipe. However, the above patent needs to set an insulating medium between the filling rubber and the steel pipe. When the filling rubber is in close contact with the pipe wall, the filling rubber will still be softened by the temperature of the pipe wall, affecting the support effect on the pipe wall.

[0005] The existing patent CN202410110092.2 discloses a push-bending forming device and a forming method for a titanium alloy pipe. A plurality of filling spheres are arranged inside the pipe blank. The material of the filling spheres is a metal material, and the diameter of the filling spheres is slightly smaller than the inner diameter of the pipe blank. The inner wall of the pipe blank is supported by the movement of the metal filling spheres inside the pipe blank, thereby improving the forming effect of the inner wall of the pipe blank. Although the metal filling spheres are less affected by temperature and can provide a large supporting force for the inner wall of the pipe blank, there is a certain gap between the elastic spheres, and the inner wall of the pipe blank cannot be effectively supported at the gap, and defects are likely to form at the pipe wall between the filling spheres. And during the production process, it is necessary to add filling spheres into the pipe blank, which affects the production effect of the bent pipe. Summary of the Invention

[0006] The object of the present invention is to provide a bending forming device and a forming method for thin-walled pipe fittings, so as to solve the problems that the existing forming device has poor supporting effect during the bending forming of thin-walled pipe fittings, affecting the forming quality and forming efficiency of the pipe fittings.

[0007] To achieve the above object, the present invention provides a bending forming device for thin-walled pipe fittings, which includes a frame. A lower die is arranged on the working table of the frame. Several lower forming cavities are arranged inside the lower die. An upper forming mechanism is arranged above the working table. An upper die adapted to the lower die is arranged on the lifting seat of the upper forming mechanism. A supporting mechanism for supporting the inside of the pipe blank is arranged on the working table. The supporting mechanism includes a first sliding seat, and supporting units corresponding to the lower forming cavities one by one are arranged on the first sliding seat. A traction mechanism for traction of the pipe blank is arranged on the working table. The traction mechanism includes a second sliding seat, and traction units corresponding to the lower forming cavities one by one are arranged on the second sliding seat. The supporting units and the traction units are respectively located at the feeding end and the discharging end of the lower forming cavity.

[0008] Preferably, the supporting unit includes a push rod. One end of the push rod is provided with a push plate for pushing the pipe blank. The diameter of the push rod is smaller than the inner diameter of the pipe blank. The diameter of the push plate is larger than the inner diameter of the pipe blank and smaller than the aperture of the lower forming cavity. The other end of the push rod is rotatably provided with a rotating shaft. The center of the end of the rotating shaft is fixedly provided with a first flexible shaft. The rotating shaft is coaxial with the push rod. The first flexible shaft is rotationally and slidably connected with the push rod. One end of the first flexible shaft extending out of the push rod is provided with a supporting head. One end of the push rod close to the first sliding seat is provided with a first mounting plate. A first mounting groove is arranged on the first sliding seat. The first mounting plate is clamped in the first mounting groove. A power structure for driving the first flexible shaft to rotate and slide is arranged between the first mounting plate and the push rod.

[0009] Preferably, the power structure includes a transmission box. One end of the transmission box is fixedly connected with the first mounting plate. The other end of the transmission box is fixedly connected with a fixing plate fixedly arranged at the end of the push rod. A gear is fixedly arranged on the outside of the rotating shaft. The gear is coaxial with the rotating shaft. A motor is arranged inside the transmission box. A driving wheel meshing with the gear is fixedly arranged on the output shaft of the motor. The motor drives the rotating shaft to rotate through the driving wheel and the gear. A transmission sleeve coaxial with the rotating shaft is fixedly arranged on the fixing plate. The transmission sleeve is located outside the rotating shaft. An annular wavy transmission groove is arranged on the inner wall of the transmission sleeve. A fixing pin adapted to the transmission groove is fixedly arranged on the rotating shaft. The fixing pin is located in the transmission groove and is slidably connected with the transmission groove. The transmission sleeve drives the rotating shaft to slide along the axis of the push rod while rotating through the transmission groove and the fixing pin.

[0010] Preferably, the supporting head includes a plurality of rigid first support plates distributed in a linear array. The diameter of the first support plate is smaller than the inner diameter of the tube blank. The first support plate is coaxial with and fixedly connected to the first flexible shaft. The edges between adjacent first support plates are connected by an elastic membrane sleeve. A closed air cavity is formed among the membrane sleeve, the first support plate and the first flexible shaft. An air passage is arranged inside the first flexible shaft. An air inlet hole communicating the air passage with the air cavity is arranged on the first flexible shaft. An air inlet pipe arranged at the center of the rotating shaft is hermetically communicated with the air passage. The air inlet pipe is communicated with an external air pump through a rotary joint. A wire passing hole for the pipeline to pass through is arranged on the side wall of the transmission box.

[0011] Preferably, a positioning sleeve is arranged outside the ejector rod. A through hole for the ejector rod to pass through is arranged at the center of the positioning sleeve. The positioning sleeve is slidably connected to the ejector rod. Guide sleeves are arranged at the feeding ends of the lower forming cavity and the upper forming cavity of the upper die. The positioning sleeve is sleeved outside the guide sleeve. A reset spring is arranged between the positioning sleeve and the push plate.

[0012] Preferably, the traction unit includes a fixed rod. A second mounting plate is fixedly arranged at one end of the fixed rod close to the second sliding seat. A second mounting groove is arranged on the second sliding seat. The second mounting plate is clamped in the second mounting groove. A second flexible shaft is slidably arranged inside the fixed rod. A flexible sleeve is arranged outside a section of the second flexible shaft extending out of the fixed rod. The flexible sleeve wraps around the second flexible shaft. One end of the flexible sleeve is fixed on the fixed rod. A plurality of second support plates distributed in a linear array are arranged on the flexible sleeve. The diameter of the second support plate is smaller than the aperture of the lower forming cavity. A traction head is arranged at the end of the flexible sleeve.

[0013] Preferably, the traction head includes a housing. The housing is fixed at the end of the flexible sleeve. The housing is slidably connected to the second flexible shaft. A transmission block is arranged inside the housing. The transmission block is fixedly connected to the second flexible shaft. The second flexible shaft is slidably connected to the fixed rod. A cylinder for driving the second flexible shaft to slide is arranged inside the fixed rod. A fixed sleeve for guiding the sliding of the transmission block is arranged inside one end of the housing close to the second flexible shaft. A plurality of top plates distributed in a circumferential array are arranged at the end of the housing far from the second flexible shaft. An arc-shaped top plate is fixedly arranged at one end of a sliding plate. The sliding plate is hinged to the transmission block through a transmission rod. An avoidance hole for the transmission rod to pass through is arranged on the housing. A track for guiding the sliding of the sliding plate is arranged on the housing. The sliding plate slides along a straight line passing through the central axis of the housing.

[0014] Preferably, the lower die is distributed in a stepped shape on the workbench. A first mounting hole is arranged at the outer bending part of the lower die close to the lower forming cavity, and a second mounting hole is arranged at the inner bending part of the lower die close to the lower forming cavity. Heating elements are arranged in both the first mounting hole and the second mounting hole. The heating elements are connected to a controller.

[0015] Preferably, a first guide rail for guiding the horizontal sliding of the first sliding seat is provided on the workbench, and a first hydraulic cylinder for driving the first sliding seat to slide is provided on the workbench; a second guide rail for guiding the horizontal sliding of the second sliding seat is provided on the workbench, and a second hydraulic cylinder for driving the second sliding seat to slide is provided on the workbench.

[0016] The forming method based on the above-mentioned thin-walled pipe fitting bending forming device includes the following steps: S1. Insert the first mounting plate into the first mounting groove on the first sliding seat, and fix the first mounting plate on the first sliding seat with screws; insert the second mounting plate into the second mounting groove on the second sliding seat, and fix the second mounting plate on the second sliding seat with screws. S2. Apply lubricant to the outer wall of the pipe blank and the support head, place the pipe blank in the lower forming cavity, and the hydraulic cylinder drives the upper die to move downward through the lifting seat, and the upper die and the lower die are closed. S3. Start the first hydraulic cylinder, and the first hydraulic cylinder drives the ejector rod to move synchronously through the first sliding seat. The ejector rod inserts the support head into the inside of one end of the pipe blank. The first support plate supports inside the pipe blank. The push plate contacts the end of the pipe blank, and the positioning sleeve is sleeved outside the guide sleeve. S4. Start the second hydraulic cylinder, and the second hydraulic cylinder drives the fixed rod to move through the second sliding seat. The fixed rod inserts the traction head into the other end of the pipe blank. During the insertion process of the traction head, the second flexible shaft moves and deforms along the lower forming cavity. The second support plate supports inside the lower forming cavity, and the housing of the traction head inserts into the other end of the pipe blank. S5. The air cylinder extends, and the air cylinder drives the second flexible shaft to slide through the piston rod. The second flexible shaft drives the transmission block to slide in the fixed sleeve. The transmission block drives the sliding plate to slide outward through the transmission rod, and the sliding plate presses tightly against the inner wall of the pipe blank through the top plate. S6. Start the heating element, and the heating element heats the outside and the inside of the lower forming cavity respectively. S7. After the lower forming cavity is heated to the set temperature, start the air pump. The air pump sends high-pressure gas into the air duct through the rotary joint. The high-pressure gas enters the air cavity through the air inlet hole, and the membrane sleeve expands, and the membrane sleeve supports the inner cavity of the pipe blank. S8. The first hydraulic cylinder extends, and the first hydraulic cylinder drives the ejector rod to move through the first sliding seat. The push plate pushes the pipe blank to move in the lower forming cavity, and the spring extends; the second hydraulic cylinder contracts, and the second hydraulic cylinder drives the fixed rod to slide outward through the second sliding seat. The fixed rod pulls the other end of the pipe blank to move outward through the top plate, and the pipe blank bends and deforms in the lower forming cavity. Meanwhile, start the motor. The motor drives the rotating shaft to rotate through the driving wheel and the gear. The rotating shaft drives the first flexible shaft to rotate, and the first flexible shaft drives the first support plate to rotate inside the tube blank. When the rotating shaft rotates, the rotating shaft drives the first flexible shaft to slide under the limitation of the fixed pin and the transmission groove, and the first flexible shaft drives the first support plate to slide. The first support plate supports the tube blank during the rotation and sliding processes. S9. After the forming is completed, the cylinder contracts. The cylinder drives the transmission block to move outwards through the second flexible shaft, and the transmission block drives the top plate to move away from the inner wall of the tube blank through the transmission rod. The first hydraulic cylinder and the second hydraulic cylinder contract, the ejector rod moves out of the tube blank, and the housing moves out of the tube blank. The contraction of the hydraulic cylinder drives the lifting seat to move upwards, and the lifting seat drives the upper die to move upwards to take out the formed tube blank from the lower forming cavity.

[0017] The advantages and positive effects of the thin-walled pipe fitting bending forming device and the forming method of the present invention are as follows: 1. In the present invention, the support unit and the traction unit are respectively located at the feeding end and the discharging end of the lower forming cavity. The moving speeds of the support unit and the traction unit are adapted to each other. The inner wall of the tube blank is supported by the support unit, and the tube blank is tractioned at the other end by the traction unit, which is beneficial to reducing the wrinkles on the inner side of the tube blank and the thinning and fracture on the outside of the tube blank, and is beneficial to improving the bending forming of the tube blank.

[0018] 2. A membrane sleeve is arranged between the support plates of the support head in the present invention. The membrane sleeve supports the inner wall of the tube blank under the action of high-pressure gas. While the flexible membrane sleeve supports the tube blank, it can make the adjacent support plates fold, meet the bending deformation of the first flexible shaft along with the lower forming cavity, and improve the support effect on the inner wall of the tube blank. The support head rotates and slides along the inner wall of the tube blank under the action of the power structure, so as to fully support the inner wall of the tube blank and improve the support effect of the support head on the tube blank.

[0019] 3. A flexible sleeve is arranged outside the second flexible shaft of the traction unit. A plurality of second support plates are arranged on the flexible sleeve in a linear array distribution. A traction head is arranged at the end of the flexible sleeve. Through the sliding of the second flexible shaft, the top plate on the traction head is driven to move, so as to press the top plate tightly against the inner wall of the pipe fitting, and the tube blank is tractioned from the end of the tube blank. The second support plate supports the traction head to improve the stability of the traction of the traction head on the tube blank.

[0020] Next, through the drawings and embodiments, the technical solutions of the present invention will be further described in detail. Description of the Drawings

[0021] Figure 1 It is a three-dimensional structural schematic diagram of an embodiment of the present invention; Figure 2 It is a three-dimensional structural schematic diagram of the workbench of an embodiment of the present invention Figure 1 ; Figure 3 Schematic three-dimensional structure of the workbench according to an embodiment of the present invention Figure 2 ; Figure 4 Schematic top view structure of the workbench according to an embodiment of the present invention; Figure 5 Schematic cross-sectional structure of the support unit according to an embodiment of the present invention; Figure 6 Schematic cross-sectional structure of the support head according to an embodiment of the present invention; Figure 7 Schematic unfolded structure of the transmission sleeve according to an embodiment of the present invention; Figure 8 Schematic three-dimensional structure of the traction unit according to an embodiment of the present invention; Figure 9 Schematic cross-sectional structure of the traction unit according to an embodiment of the present invention; Figure 10 Schematic cross-sectional structure of the traction head according to an embodiment of the present invention.

[0022] Reference numerals 1, frame; 11, workbench; 12, lower die; 13, lower forming cavity; 14, first mounting hole; 15, second mounting hole; 16, first guide rail; 17, second guide rail; 18, guide sleeve; 2, support mechanism; 21, first sliding seat; 22, first hydraulic cylinder; 23, ejector rod; 24, fixing plate; 25, transmission box; 26, first mounting plate; 27, first mounting groove; 28, rotating shaft; 29, gear; 210, transmission sleeve; 211, first flexible shaft; 212, first support plate; 213, membrane sleeve; 214, air cavity; 215, air duct; 216, air inlet hole; 217, rotary joint; 218, wire passing hole; 219, push plate; 220, positioning sleeve; 221, spring; 222, transmission groove; 3, traction mechanism; 31, second sliding seat; 32, second hydraulic cylinder; 33, fixing rod; 34, second mounting plate; 35, second mounting groove; 36, second flexible shaft; 37, second support plate; 38, housing; 39, cylinder; 310, transmission block; 311, sliding plate; 312, top plate; 313, avoidance hole; 314, transmission rod; 315, fixing sleeve; 4, upper forming mechanism; 41, upper die; 42, lifting seat. Detailed implementation manners

[0023] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the inventive product is customarily placed during use. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention. In the description of the present invention, it should also be noted that unless otherwise clearly specified and defined, the terms "set", "installed", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can 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.

[0024] In this application, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. In case of inconsistency, the meaning described in this specification or the meaning derived from the content recorded in this specification shall prevail. In addition, the terms used herein are only for the purpose of describing the embodiments of this application and are not intended to limit this application.

[0025] The following will describe in detail the embodiments of the present invention with reference to the accompanying drawings.

[0026] As Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 shown. A thin-walled pipe fitting bending and forming device includes a frame 1. A lower die 12 is fixedly arranged on the workbench 11 of the frame 1. A plurality of lower forming cavities 13 are arranged inside the lower die 12. In this embodiment, three lower forming cavities 13 are arranged. The lower die 12 is distributed in a stepped manner on the workbench 11 to facilitate the forming of the pipe blank in different lower forming cavities 13. A first mounting hole 14 is arranged near the outer bending part of the lower forming cavity 13, and a second mounting hole 15 is arranged near the inner bending part of the lower forming cavity 13. Heating elements are arranged in both the first mounting hole 14 and the second mounting hole 15, and the heating elements are connected to a controller. The heating elements are heating rods. The heating rods heat the outer and inner sides of the lower forming cavity 13 respectively, heating the outer and inner sides to their respective set temperatures to meet the requirements of different deformations of the inner and outer sides of the pipe blank during the deformation process. Thermocouples are arranged on both the inner and outer sides of the lower forming cavity 13 for measuring the temperatures of the inner and outer sides.

[0027] Above the workbench 11, an upper forming mechanism 4 is provided. On the lifting seat 42 of the upper forming mechanism 4, an upper die 41 adapted to the lower die 12 is fixedly arranged. On the lower surface of the upper die 41, an upper forming cavity is provided. After the upper forming cavity and the lower forming cavity 13 are combined, a complete forming cavity is formed. The support seat of the upper forming mechanism 4 is fixed on the workbench 11, and a hydraulic cylinder for driving the lifting of the lifting seat 42 is arranged on the support seat.

[0028] On the workbench 11, a support mechanism 2 for supporting the inside of the tube blank is provided. The support mechanism 2 includes a first sliding seat 21, and support units corresponding to the lower forming cavities 13 one by one are arranged on the first sliding seat 21. On the workbench 11, a traction mechanism 3 for traction of the tube blank is provided. The traction mechanism 3 includes a second sliding seat 31, and traction units corresponding to the lower forming cavities 13 one by one are arranged on the second sliding seat 31. The support units and the traction units are respectively located at the feeding end and the discharging end of the lower forming cavity 13. The moving speeds of the support unit and the traction unit are adapted to each other. By supporting the inner wall of the tube blank through the support unit and traction at the other end of the tube blank through the traction unit, it is beneficial to reduce the wrinkles on the inner side of the tube blank and the thinning and fracture on the outside of the tube blank, and is beneficial to improve the bending forming of the tube blank.

[0029] On the workbench 11, a first guide rail 16 for guiding the horizontal sliding of the first sliding seat 21 is fixedly arranged, and a first hydraulic cylinder 22 for driving the sliding of the first sliding seat 21 is arranged on the workbench 11. On the workbench 11, a second guide rail 17 for guiding the horizontal sliding of the second sliding seat 31 is fixedly arranged, and a second hydraulic cylinder 32 for driving the sliding of the second sliding seat 31 is arranged on the workbench 11.

[0030] As Figure 5 shown. The support unit includes a push rod 23, and a push plate 219 for pushing the tube blank is arranged at one end of the push rod 23. The diameter of the push rod 23 is smaller than the inner diameter of the tube blank, and the diameter of the push plate 219 is larger than the inner diameter of the tube blank and smaller than the aperture of the lower forming cavity 13. In this way, the end of the push rod 23 can be inserted into the inside of the tube blank, and the push plate 219 is inserted into the lower forming cavity 13 to push the tube blank. The other end of the push rod 23 is rotatably provided with a rotating shaft 28 through a bearing. A first flexible shaft 211 is fixedly arranged at the center of the end of the rotating shaft 28. The rotating shaft 28 is coaxial with the push rod 23, and the first flexible shaft 211 is rotationally and slidably connected with the push rod 23. A support head is arranged at one end of the first flexible shaft 211 extending out of the push rod 23, and the support head is inserted into the inside of the tube blank to support the inner wall of the tube blank. A first mounting plate 26 is arranged at one end of the push rod 23 close to the first sliding seat 21, and a first mounting groove 27 is arranged on the first sliding seat 21. The first mounting plate 26 is clamped in the first mounting groove 27.

[0031] A power structure for driving the rotation and sliding of the first flexible shaft 211 is provided between the first mounting plate 26 and the ejector rod 23. The power structure includes a transmission box 25. One end of the transmission box 25 is fixedly connected to the first mounting plate 26, and the other end of the transmission box 25 is fixedly connected to a fixing plate 24 fixedly arranged at the end of the ejector rod 23. A gear 29 is fixedly arranged on the outer part of the rotating shaft 28, and the gear 29 is coaxial with the rotating shaft 28. A motor is arranged inside the transmission box 25, and a driving wheel meshing with the gear 29 is fixedly arranged on the output shaft of the motor. The motor drives the rotating shaft 28 to rotate through the driving wheel and the gear 29.

[0032] As Figure 7 shown. A transmission sleeve 210 coaxial with the rotating shaft 28 is fixedly arranged on the fixing plate 24, and the transmission sleeve 210 is located outside the rotating shaft 28. An annular wavy transmission groove 222 is arranged on the inner wall of the transmission sleeve 210. A fixing pin adapted to the transmission groove 222 is fixedly arranged on the rotating shaft 28, and the fixing pin is located in the transmission groove 222 and is slidably connected with the transmission groove 222. The transmission sleeve 210 drives the rotating shaft 28 to slide along the axis of the ejector rod 23 while rotating through the transmission groove 222 and the fixing pin.

[0033] As Figure 6 shown. The supporting head includes a plurality of rigid first supporting plates 212 distributed in a linear array. The diameter of the first supporting plate 212 is slightly smaller than the inner diameter of the tube blank, and the first supporting plate 212 supports the inner wall of the tube blank. The first supporting plate 212 is coaxial with and fixedly connected to the first flexible shaft 211. The edges between adjacent first supporting plates 212 are connected by an elastic membrane sleeve 213, and the membrane sleeve 213 is a heat-resistant rubber sleeve. A closed air cavity 214 is formed among the membrane sleeve 213, the first supporting plate 212 and the first flexible shaft 211. The high-pressure gas in the air cavity 214 deforms the membrane sleeve 213, so that the membrane sleeve 213 closely adheres to the inner wall of the tube blank to support the tube blank. An air passage 215 is arranged inside the first flexible shaft 211, and an air inlet hole 216 for communicating the air passage 215 with the air cavity 214 is arranged on the first flexible shaft 211. An air inlet pipe arranged at the center of the rotating shaft 28 is hermetically communicated with the air passage 215, and the air inlet pipe is communicated with an external air pump through a rotary joint 217. A wire passing hole 218 for allowing the pipeline to pass through is arranged on the side wall of the transmission box 25.

[0034] A membrane sleeve 213 is arranged between the supporting plates of the supporting head. The membrane sleeve 213 supports the inner wall of the tube blank under the action of high-pressure gas. The flexible membrane sleeve 213 can fold the adjacent supporting plates while supporting the tube blank, so as to meet the bending deformation of the first flexible shaft 211 along with the lower forming cavity 13 and improve the supporting effect on the inner wall of the tube blank. The supporting head rotates and slides along the inner wall of the tube blank under the action of the power structure, so as to fully support the inner wall of the tube blank and improve the supporting effect of the supporting head on the tube blank.

[0035] A positioning sleeve 220 is arranged outside the ejector rod 23. A through hole for the ejector rod 23 to pass through is arranged at the center of the positioning sleeve 220. The aperture of the through hole is slightly larger than the outer diameter of the ejector rod 23, and the positioning sleeve 220 is slidably connected with the ejector rod 23. Guide sleeves 18 are arranged at the feeding ends of the lower forming cavity 13 and the upper forming cavity of the upper die 41. The positioning sleeve 220 is sleeved outside the guide sleeve 18. The positioning sleeve 220 supports the ejector rod 23, so that the ejector rod 23 is always located at the center of the tube blank. A reset spring 221 is arranged between the positioning sleeve 220 and the push plate 219 to facilitate the reset of the positioning sleeve 220.

[0036] As Figure 8 , Figure 9 shown. The traction unit includes a fixed rod 33. A second mounting plate 34 is fixedly arranged at one end of the fixed rod 33 close to the second sliding seat 31. A second mounting groove 35 is arranged on the second sliding seat 31, and the second mounting plate 34 is clamped in the second mounting groove 35. A second flexible shaft 36 is slidably arranged inside the fixed rod 33. A flexible sleeve is arranged outside a section of the second flexible shaft 36 extending out of the fixed rod 33. The flexible sleeve wraps around the outside of the second flexible shaft 36, and the flexible sleeve is slidably connected with the second flexible shaft 36. One end of the flexible sleeve is fixed on the fixed rod 33. A number of second support plates 37 are arranged on the flexible sleeve in a linear array. The diameter of the second support plate 37 is smaller than the aperture of the lower forming cavity 13. A traction head is arranged at the end of the flexible sleeve. The flexible sleeve has a certain stiffness, so that the flexible sleeve can bend along with the bending of the second flexible shaft 36, and has a certain support for the second support plates 37 and the traction head, maintaining the distance between adjacent second support plates 37 and the traction head at the connection of the flexible sleeve. The diameter of the second support plate 37 is slightly smaller than the aperture of the lower forming cavity 13, so that the second support plate 37 can just be inserted into the inside of the lower forming cavity 13. The second support plate 37 supports the traction head. Adjacent second support plates 37 can be folded to meet the bending deformation of the second flexible shaft 36 along with the lower forming cavity 13 and insert the traction head into the inside of the tube blank.

[0037] As Figure 10As shown. The towing head includes a housing 38. One end of the housing 38 is provided with a through hole for inserting the second flexible shaft 36. The second flexible shaft 36 is slidably connected to the housing 38. The housing 38 is fixed to the end of the flexible sleeve. Inside the housing 38, there is a transmission block 310 which is fixedly connected to the second flexible shaft 36. The second flexible shaft 36 is slidably connected to the fixed rod 33. Inside the fixed rod 33, there is a cylinder 39 for driving the second flexible shaft 36 to slide. Inside one end of the housing 38 close to the second flexible shaft 36, there is a fixed sleeve 315 which plays a guiding role in the sliding of the transmission block 310. At the end of the housing 38 far from the second flexible shaft 36, there are several top plates 312 distributed in a circumferential array. The arc-shaped top plates 312 are fixedly arranged at one end of the sliding plate 311. The sliding plate 311 is hinged to the transmission block 310 through a transmission rod 314. There is an avoidance hole 313 on the housing 38 for the transmission rod 314 to pass through. On the housing 38, there is a track which plays a guiding role in the sliding of the sliding plate 311. The sliding plate 311 slides along a straight line passing through the central axis of the housing 38.

[0038] The forming method based on the above-mentioned thin-walled pipe fitting bending forming device includes the following steps: S1. Insert the first mounting plate 26 into the first mounting groove 27 on the first sliding seat 21, and fix the first mounting plate 26 on the first sliding seat 21 with screws. Insert the second mounting plate 34 into the second mounting groove 35 on the second sliding seat 31, and fix the second mounting plate 34 on the second sliding seat 31 with screws.

[0039] S2. Apply lubricant to the outer wall of the pipe blank and the support head, place the pipe blank in the lower forming cavity 13, and the hydraulic cylinder drives the upper die 41 to move downward through the lifting seat 42, and the upper die 41 and the lower die 12 are closed.

[0040] S3. Start the first hydraulic cylinder 22. The first hydraulic cylinder 22 drives the ejector rod 23 to move synchronously through the first sliding seat 21. The ejector rod 23 inserts the support head into the inside of one end of the pipe blank. The first support plate 212 supports inside the pipe blank. The push plate 219 contacts the end of the pipe blank. The positioning sleeve 220 is sleeved outside the guiding sleeve 18.

[0041] S4. Start the second hydraulic cylinder 32. The second hydraulic cylinder 32 drives the fixed rod 33 to move through the second sliding seat 31. The fixed rod 33 inserts the towing head into the other end of the pipe blank. During the insertion process of the towing head, the second flexible shaft 36 moves and deforms along the lower forming cavity 13. The second support plate 37 supports inside the lower forming cavity 13, and the housing 38 of the towing head is inserted into the other end of the pipe blank.

[0042] S5. The cylinder 39 extends. The cylinder 39 drives the second flexible shaft 36 to slide through the piston rod. The second flexible shaft 36 drives the transmission block 310 to slide within the fixed sleeve 315. The transmission block 310 drives the slide plate 311 to slide outwards through the transmission rod 314. The slide plate 311 presses tightly against the inner wall of the tube blank through the top plate 312.

[0043] S6. Start the heating element. The heating element heats the outer side and the inner side of the lower forming cavity 13 respectively. S7. After the lower forming cavity 13 is heated to the set temperature, start the air pump. The air pump sends high-pressure gas into the air passage 215 through the rotary joint 217. The high-pressure gas enters the air cavity 214 through the air inlet hole 216. The membrane sleeve 213 expands, and the membrane sleeve 213 supports the inner cavity of the tube blank.

[0044] S8. The first hydraulic cylinder 22 extends. The first hydraulic cylinder 22 drives the ejector rod 23 to move through the first slide seat 21. The push plate 219 pushes the tube blank to move within the lower forming cavity 13, and the spring 221 extends. The second hydraulic cylinder 32 contracts. The second hydraulic cylinder 32 drives the fixed rod 33 to slide outwards through the second slide seat 31. The fixed rod 33 pulls the other end of the tube blank to move outwards through the top plate 312, and the tube blank is bent and deformed within the lower forming cavity 13.

[0045] Meanwhile, start the motor. The motor drives the rotating shaft 28 to rotate through the driving wheel and the gear 29. The rotating shaft 28 drives the first flexible shaft 211 to rotate. The first flexible shaft 211 drives the first support plate 212 to rotate within the tube blank. When the rotating shaft 28 rotates, the rotating shaft 28 drives the first flexible shaft 211 to slide under the limitation of the fixed pin and the transmission groove 222. The first flexible shaft 211 drives the first support plate 212 to slide. The first support plate 212 supports the tube blank during the rotation and sliding processes.

[0046] S9. After the forming is completed, the cylinder 39 contracts. The cylinder 39 drives the transmission block 310 to move outwards through the second flexible shaft 36. The transmission block 310 drives the top plate 312 to move away from the inner wall of the tube blank through the transmission rod 314. The air pump pumps air, and the gas in the air cavity 214 is released. The first hydraulic cylinder 22 and the second hydraulic cylinder 32 contract. The ejector rod 23 moves out of the tube blank, and the housing 38 moves out of the tube blank. The contraction of the hydraulic cylinder drives the lifting seat 42 to move upwards. The lifting seat 42 drives the upper die 41 to move upwards, and the formed tube blank is taken out from the lower forming cavity 13.

[0047] Therefore, by using the thin-walled pipe fitting bending forming device and the forming method of the present invention, the problems that the existing forming device has poor supporting effect during the bending forming of thin-walled pipe fittings, affecting the forming quality and forming efficiency of the pipe fittings can be solved.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. 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 they can still modify or equivalently replace the technical solutions of the present invention, and these modifications or equivalent replacements do not enable the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A bending and forming device for thin-walled pipe fittings, characterized in that: It includes a frame. A lower die is arranged on the workbench of the frame. Several lower forming cavities are arranged inside the lower die. An upper forming mechanism is arranged above the workbench. An upper die adapted to the lower die is arranged on the lifting seat of the upper forming mechanism. A supporting mechanism for supporting the inside of the tube blank is arranged on the workbench. The supporting mechanism includes a first sliding seat, and supporting units corresponding to the lower forming cavities one by one are arranged on the first sliding seat. A traction mechanism for traction of the tube blank is arranged on the workbench. The traction mechanism includes a second sliding seat, and traction units corresponding to the lower forming cavities one by one are arranged on the second sliding seat. The supporting units and the traction units are respectively located at the feeding end and the discharging end of the lower forming cavity.

2. The thin-walled pipe fitting bending and forming device according to claim 1, characterized in that: The supporting unit includes a ejector rod. A push plate for pushing the tube blank is arranged at one end of the ejector rod. The diameter of the ejector rod is smaller than the inner diameter of the tube blank. The diameter of the push plate is larger than the inner diameter of the tube blank and smaller than the aperture of the lower forming cavity. A rotating shaft is rotatably arranged at the other end of the ejector rod. A first flexible shaft is fixedly arranged at the center of the end of the rotating shaft. The rotating shaft is coaxial with the ejector rod. The first flexible shaft is rotationally and slidably connected with the ejector rod. A supporting head is arranged at the end of the first flexible shaft extending out of the ejector rod. A first mounting plate is arranged at one end of the ejector rod close to the first sliding seat. A first mounting groove is arranged on the first sliding seat. The first mounting plate is clamped in the first mounting groove. A power structure for driving the first flexible shaft to rotate and slide is arranged between the first mounting plate and the ejector rod.

3. The thin-walled pipe bending and forming device according to claim 2, characterized in that: The power structure includes a transmission box. One end of the transmission box is fixedly connected with the first mounting plate. The other end of the transmission box is fixedly connected with a fixing plate fixedly arranged at the end of the ejector rod. A gear is fixedly arranged on the outer part of the rotating shaft. The gear is coaxial with the rotating shaft. A motor is arranged inside the transmission box. A driving wheel meshing with the gear is fixedly arranged on the output shaft of the motor. The motor drives the rotating shaft to rotate through the driving wheel and the gear. A transmission sleeve coaxial with the rotating shaft is fixedly arranged on the fixing plate. The transmission sleeve is located on the outer part of the rotating shaft. An annular wavy transmission groove is arranged on the inner wall of the transmission sleeve. A fixing pin adapted to the transmission groove is fixedly arranged on the rotating shaft. The fixing pin is located in the transmission groove and is slidably connected with the transmission groove. The transmission sleeve drives the rotating shaft to slide along the axis of the ejector rod while rotating through the transmission groove and the fixing pin.

4. A thin-walled pipe fitting bending and forming device according to claim 3, characterized in that: The supporting head includes several rigid first supporting plates distributed in a linear array. The diameter of the first supporting plate is smaller than the inner diameter of the tube blank. The first supporting plate is coaxial with and fixedly connected to the first flexible shaft. The edges between adjacent first supporting plates are connected by an elastic membrane sleeve. An enclosed air cavity is formed among the membrane sleeve, the first supporting plate and the first flexible shaft. An air passage is arranged inside the first flexible shaft. An air inlet hole for communicating the air passage with the air cavity is arranged on the first flexible shaft. An air inlet pipe arranged at the center of the rotating shaft is hermetically communicated with the air passage. The air inlet pipe is communicated with an external air pump through a rotary joint. A wire passing hole for the pipeline to pass through is arranged on the side wall of the transmission box.

5. The thin-walled pipe bending and forming device according to claim 4, wherein: A positioning sleeve is arranged on the outer part of the ejector rod. A through hole for the ejector rod to pass through is arranged at the center of the positioning sleeve. The positioning sleeve is slidably connected with the ejector rod. Guide sleeves are arranged at the feeding ends of the lower forming cavity and the upper forming cavity of the upper die. The positioning sleeve is sleeved on the outer part of the guide sleeve. A spring for resetting is arranged between the positioning sleeve and the push plate.

6. The thin-walled pipe bending and forming device according to claim 5, characterized in that: The traction unit includes a fixed rod. At one end of the fixed rod close to the second sliding seat, a second mounting plate is fixedly arranged. A second mounting groove is provided on the second sliding seat, and the second mounting plate is clamped in the second mounting groove. A second flexible shaft is slidably arranged inside the fixed rod. One section of the second flexible shaft extending out of the fixed rod is externally provided with a flexible sleeve. The flexible sleeve wraps around the outside of the second flexible shaft. One end of the flexible sleeve is fixed on the fixed rod. A number of second support plates are arranged on the flexible sleeve in a linear array. The diameter of the second support plate is smaller than the aperture of the lower forming cavity. A traction head is arranged at the end of the flexible sleeve.

7. The thin-walled pipe bending and forming device according to claim 6, wherein: The traction head includes a housing. The housing is fixed at the end of the flexible sleeve. The housing is slidably connected to the second flexible shaft. A transmission block is arranged inside the housing. The transmission block is fixedly connected to the second flexible shaft. The second flexible shaft is slidably connected to the fixed rod. A cylinder for driving the second flexible shaft to slide is arranged inside the fixed rod. A fixed sleeve for guiding the sliding of the transmission block is arranged inside one end of the housing close to the second flexible shaft. A number of top plates are arranged at the end of the housing far from the second flexible shaft in a circumferential array. The arc-shaped top plate is fixedly arranged at one end of the sliding plate. The sliding plate is hinged to the transmission block through a transmission rod. An avoidance hole for the transmission rod to pass through is arranged on the housing. A track for guiding the sliding of the sliding plate is arranged on the housing. The sliding plate slides along a straight line passing through the central axis of the housing.

8. A thin-walled pipe fitting bending and forming device according to claim 7, characterized in that: The lower die is distributed in a stepped shape on the workbench. A first mounting hole is arranged on the lower die close to the outer bending part of the lower forming cavity, and a second mounting hole is arranged close to the inner bending part of the lower forming cavity. Heating elements are arranged in both the first mounting hole and the second mounting hole. The heating elements are connected to the controller.

9. The thin-walled pipe bending and forming device according to claim 8, characterized in that: A first guide rail for guiding the horizontal sliding of the first sliding seat is arranged on the workbench, and a first hydraulic cylinder for driving the first sliding seat to slide is arranged on the workbench; a second guide rail for guiding the horizontal sliding of the second sliding seat is arranged on the workbench, and a second hydraulic cylinder for driving the second sliding seat to slide is arranged on the workbench.

10. A forming method for a thin-walled pipe fitting bending and forming device according to claim 9, characterized in that, It includes the following steps: S1. Insert the first mounting plate into the first mounting groove on the first sliding seat, and fix the first mounting plate on the first sliding seat with screws; insert the second mounting plate into the second mounting groove on the second sliding seat, and fix the second mounting plate on the second sliding seat with screws; S2. Apply lubricant to the outer wall of the tube blank and the support head, place the tube blank in the lower forming cavity, and the hydraulic cylinder drives the upper die to move downward through the lifting seat, and the upper die and the lower die are closed; S3. Start the first hydraulic cylinder. The first hydraulic cylinder drives the ejector rod to move synchronously through the first sliding seat. The ejector rod inserts the support head into the inside of one end of the tube blank. The first support plate supports inside the tube blank. The push plate contacts the end of the tube blank. The positioning sleeve is sleeved outside the guide sleeve; S4. Start the second hydraulic cylinder. The second hydraulic cylinder drives the fixed rod to move through the second sliding seat. The fixed rod inserts the traction head into the other end of the tube blank. During the insertion process of the traction head, the second flexible shaft moves and deforms along the lower forming cavity. The second support plate supports inside the lower forming cavity. The housing of the traction head is inserted into the other end of the tube blank; S5. The cylinder extends. The cylinder drives the second flexible shaft to slide through the piston rod. The second flexible shaft drives the transmission block to slide within the fixed sleeve. The transmission block drives the slide plate to slide outwards through the transmission rod. The slide plate presses tightly against the inner wall of the tube blank through the top plate. S6. Start the heating element. The heating element heats the outer side and the inner side of the lower forming cavity respectively. S7. After the lower forming cavity is heated to the set temperature, start the air pump. The air pump sends high-pressure gas into the air passage through the rotary joint. The high-pressure gas enters the air cavity through the air inlet holes. The membrane sleeve expands, and the membrane sleeve supports the inner cavity of the tube blank. S8. The first hydraulic cylinder extends. The first hydraulic cylinder drives the ejector rod to move through the first sliding seat. The push plate pushes the tube blank to move within the lower forming cavity, and the spring extends. The second hydraulic cylinder contracts. The second hydraulic cylinder drives the fixed rod to slide outwards through the second sliding seat. The fixed rod pulls the other end of the tube blank to move outwards through the top plate. The tube blank is bent and deformed within the lower forming cavity. Meanwhile, start the motor. The motor drives the rotating shaft to rotate through the driving wheel and the gear. The rotating shaft drives the first flexible shaft to rotate. The first flexible shaft drives the first support plate to rotate within the tube blank. When the rotating shaft rotates, the rotating shaft drives the first flexible shaft to slide under the limitation of the fixed pin and the transmission groove. The first flexible shaft drives the first support plate to slide. The first support plate supports the tube blank during the rotation and sliding processes. S9. After the forming is completed, the cylinder contracts. The cylinder drives the transmission block to move outwards through the second flexible shaft. The transmission block drives the top plate to move away from the inner wall of the tube blank through the transmission rod. The first hydraulic cylinder and the second hydraulic cylinder contract. The ejector rod moves out of the tube blank, and the housing moves out of the tube blank. The contraction of the hydraulic cylinder drives the lifting seat to move upwards. The lifting seat drives the upper die to move upwards to take out the formed tube blank from the lower forming cavity.

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