Push-bending device for pipe with small bending radius and using method of push-bending device

Abstract

The invention provides a small-bending-radius pipe push-bending device and a using method thereof.The small-bending-radius pipe push-bending device comprises an upper supporting plate, a push rod, a hydraulic pressurizing pipe, a guide sleeve, a push-bending mold, a sealing joint, a sealing ring, a rubber ball, a pressure sensor, a hydraulic pushing cylinder, a movable ball joint and a hydraulic pressurizer. The using method comprises the following steps that firstly, a straight pipe needing to be machined is installed on the inner side of the push-bending mold; the guide rod is attached to the guide sleeve; a plurality of rubber balls are filled in the inner cavity of the straight pipe; a gap of an inner cavity of the straight pipe is filled through the hydraulic pressurizer; starting the press to apply downward pressure to the push rod; the liquid filling pressure is set to pressurize and support the interior of the pipe, and the pipe begins to be bent and formed along with descending of the push rod; and after 90-degree bending forming is completed, the liquid filling pressure is gradually increased for pressurization shaping. By adopting the mode of filling gaps with rubber balls and hydraulic pressure, the supporting pressure in the pipe is improved; and by adopting a differential friction form, the length of a linear section is increased, and meanwhile uniform stress in the bending process is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of aerospace vehicles, and in particular to a small bending radius pipe push-bending device and a use method thereof. Background Art

[0002] The layout space of aerospace vehicles, especially launch vehicles, is becoming more and more compact, and the layout options are becoming less and less. For the design of the pipeline system, the smaller the relative bending radius R / D (R is the bending radius of the bend, and D is the outer diameter of the bend) of the pipe bending parts (R / D≤1.5), the longer the straight section, the more effective it is to reduce the number of welds, and the more valuable it is. Especially in the design of the booster transmission system pipeline, in order to save space and reduce welds, thin-walled small bending radius conduit elbows are widely used. The use of thin-walled (t<1.5mm) small bending radius pipes can greatly save space and reduce the weight of the pipeline system. This advantage is particularly important for the pipeline system of the launch vehicle, especially for the extremely small bending radius bends (R / D≈1), which also increase year by year, resulting in the increasing difficulty of manufacturing such products in actual production. At present, the production of such conduits adopts the process of half-tube welding + straight pipe butt welding, and the process is heavily dependent on manual operation. A large number of complex conduits rely solely on manual repair, welding, assembly and other work. This operation mode has low manufacturing efficiency, low product quality stability, long processing cycle (more than 15 hours), and high processing cost, which affects the progress of aerospace product development and production.

[0003] After investigation, it is found that currently small bending radius tubes can be processed by push bending technology. Push bending forming operation is simple and convenient, and has a significant effect in forming small bending radius tubes, especially in avoiding thinning of the outer side of the tube when it is bent. The bending radius can reach less than 1D. However, for the push bending forming process, increasing the length of the straight section becomes the biggest difficulty. Generally, the length of the straight section L is within 1D. When the straight section is further increased, it is easy to have thinning and cracking on the outer side, wrinkling on the inner side, and cross-sectional distortion defects.

[0004] The invention patent (publication number CN114346026A) invented a push bending device, which uses the friction generated by the contact between the tube blank and the bending die rotating wheel to reduce the defects of thickening and wrinkling on the inner side of the bending part of the bent tube, but cannot solve the defects of thinning and cracking on the outer side, and the quality of the finished product is not high enough.

[0005] The invention patent (publication number CN110814121B) invented a small bending radius push-bending method for small diameter tubes and small diameter tubes. The method mainly uses low-melting point metal as a filling medium for push-bending of small diameter tubes. During the push-bending process, a partition needs to be set to isolate the low-melting point metal from the tube blank. The metal needs to be heated and separated later, but the filling effect is not flexible enough.

[0006] The invention patent (publication number CN100384558C) invented a thin-walled tube variable curvature push-bending process and mold. This method uses a hydraulic press as a loading method. There is no filling medium inside the tube during the push-bending process, and it is not suitable for tubes with high precision requirements.

[0007] The invention patent (publication number CN109158458B) invented a method for hydraulic bending of pipes using a composite filling medium. This method uses a composite method of filling a polyurethane ring inside the pipe and the action of liquid, and adopts a press bending process for forming. However, the polyurethane ring filling is prone to produce local hanging areas, which is not suitable for pipes with small bending radius.

[0008] Therefore, it is necessary to provide a small bending radius tube push-bending device and a method of using the same, which can reduce circumferential and longitudinal welds through integral forming and effectively improve product accuracy and reliability. Summary of the invention

[0009] In view of the defects in the prior art, an object of the present invention is to provide a small bending radius pipe push-bending device and a method of using the same.

[0010] According to the present invention, a small bending radius pipe push-bending device includes: a push rod, a push-bending mold, a rubber ball, a hydraulic push cylinder, a movable ball joint and a hydraulic booster, wherein the push-bending mold is installed on the lower table of the hydraulic press, a guide sleeve is installed inside the push-bending mold, and the guide sleeve includes a vertical section and a curved section. The straight pipe to be processed is installed in the vertical section of the guide sleeve and the two are arranged in close contact, and a plurality of the rubber balls are filled in the straight pipe;

[0011] The upper end of the push rod is fixedly mounted on the lower side of the upper table of the hydraulic press, and the lower end of the push rod extends into the guide sleeve and is tightly abutted against the upper end of the straight pipe through the upper sealing member;

[0012] The output end of the hydraulic booster is connected to a hydraulic boost pipe, and the hydraulic boost pipe passes through the upper sealing member and extends into the straight pipe;

[0013] The spherical end of the movable ball joint is tightly pressed against the lower end of the straight pipe through a lower sealing member, and the other end of the movable ball joint is connected to the hydraulic jacking cylinder.

[0014] Preferably, the inner cavity profile of the curved section of the guide sleeve includes only an outer curved profile, and the outer friction coefficient of the inner cavity profile of the guide sleeve is 0.8, and the inner friction coefficient is 1.6.

[0015] Preferably, the guide sleeve is fitted with the push-bending mold, the inner cavity of the push-bending mold includes a vertical section, a curved section and a horizontal section, and the curved section of the guide sleeve is smoothly connected with the horizontal section of the push-bending mold.

[0016] Preferably, the movable ball joint extends inward from the horizontal section opening of the push-bending mold to connect with the straight pipe, and the diameter of the spherical end of the movable ball joint matches the inner diameter of the guide sleeve.

[0017] Preferably, the upper sealing member comprises a sealing joint and a sealing ring, the sealing joint is arranged inside the upper end of the straight pipe, one or more sealing rings are arranged on the circumference of the sealing joint, and the sealing joint is sealingly connected to the straight pipe via the sealing ring.

[0018] Preferably, a through hole is opened at the center of the sealing joint, the hydraulic boosting pipe passes through the through hole and extends into the straight pipe, and the hydraulic boosting pipe is interference fit with the through hole.

[0019] Preferably, the lower sealing member comprises a rubber block, which is installed inside the lower end of the straight pipe and is sealed to the straight pipe.

[0020] Preferably, the push rod is fastened to the lower side of the upper table of the hydraulic press through an upper support plate.

[0021] Preferably, a pressure sensor is installed inside the movable ball joint.

[0022] A method for using a small bending radius tube push-bending device provided by the present invention is applied to the above-mentioned small bending radius tube push-bending device, comprising the following steps:

[0023] Step S1, installing the straight pipe to be processed in the push-bending die, fitting it with the guide sleeve, and installing the movable ball joint at the lower opening of the push-bending die;

[0024] Step S2, filling a plurality of rubber balls into the inner cavity of the straight tube to be processed and compacting them, and installing the lower end of the push rod on the upper end of the straight tube to be processed;

[0025] Step S3, the hydraulic booster injects water into the inner part of the straight pipe to be processed through the hydraulic booster pipe to complete the filling of the inner cavity gap of the straight pipe to be processed, and the press machine is started to apply a preset downward force F to the push rod, and presses down at a constant preset speed, setting the filling pressure P 初始 Provide pressurized support inside the straight pipe;

[0026] Step S4, at the hydraulic pressure P 初始 With the support of, as the push rod moves downward, the straight tube begins to bend and form, the movable ball joint applies a push-out force to support the rubber ball and liquid inside the straight tube, and moves back with it. After the 90° bending is completed, the filling pressure is gradually increased to pressurize and shape the inside of the straight tube. After the shaping is completed, the pressure is unloaded, the rubber ball and the formed bent pipe parts are taken out, and the processing procedure is completed.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. The present invention increases the supporting pressure inside the pipe by using a rubber ball and hydraulic pressure to fill the gap, thereby increasing the rigidity of the straight section of the pipe and effectively preventing instability and wrinkling during the bending process; by using differential friction, the friction coefficient of the straight section of the pipe is reduced, and the friction coefficient of the inner and outer sides of the bend are differentially adjusted, thereby increasing the length of the straight section and achieving uniform force during the bending process; the overall forming reduces the circumferential and longitudinal welds, improves product precision and reliability, and greatly simplifies the production process.

[0029] 2. The present invention can realize pressurized expansion of the pipe after push-bending by filling liquid through liquid filling. The rubber ball structure is adopted, the filling effect is better, and it is not easy to produce hanging areas. The surface of the bent pipe is molded and shaped, the mold accuracy of the parts after forming is improved, the springback of the parts is reduced, and high-precision processing is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0031] Figure 1 This is a cross-sectional view of a small bending radius pipe push bending device in Embodiment 1 of the present invention;

[0032] Figure 2 The present invention mainly embodies Figure 1 A magnified view of the part A in the middle;

[0033] Figure 3 The present invention mainly embodies the schematic diagram of the bent pipe after forming;

[0034] Figure 4 This is a schematic diagram of step S1 in Embodiment 2 of the present invention;

[0035] Figure 5 This is a schematic diagram of step S2 in Embodiment 2 of the present invention;

[0036] Figure 6 This is a schematic diagram of step S3 in Embodiment 2 of the present invention;

[0037] Figure 7 This is a schematic diagram of step S4 in Embodiment 2 of the present invention.

[0038] As shown in the figure:

[0039] Upper support plate 1 Push rod 2 Hydraulic booster pipe 3

[0040] Guide sleeve 4 Push bending die 5 Sealing joint 6

[0041] Sealing ring 7 Rubber ball 8 Pressure sensor 9

[0042] Hydraulic push cylinder 10 movable ball joint 11 hydraulic booster 12 DETAILED DESCRIPTION

[0043] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0044] Example 1

[0045] like Figure 1-3 As shown, a small bending radius pipe pushing and bending device provided according to the present invention includes: a push rod 2, a pushing and bending mold 5, a rubber ball 8, a hydraulic push cylinder 10, a movable ball joint 11 and a hydraulic booster 12. The pushing and bending mold 5 is installed on the lower table of the hydraulic press, and a guide sleeve 4 is installed inside the pushing and bending mold 5. The guide sleeve 4 includes a vertical section and a curved section. The straight pipe to be processed is installed in the vertical section of the guide sleeve 4 and the two are arranged in a close fit. The straight pipe is filled with a plurality of rubber balls 8; the upper end of the push rod 2 is fastened to the lower side of the upper table of the hydraulic press, and the lower end of the push rod 2 extends into the guide sleeve 4 and is tightly pressed against the upper end of the straight pipe through an upper seal; the output end of the hydraulic booster 12 is connected to a hydraulic boosting pipe 3, and the hydraulic boosting pipe 3 passes through the upper seal and extends into the straight pipe; the spherical end of the movable ball joint 11 is tightly pressed against the lower end of the straight pipe through a lower seal, and the other end of the movable ball joint 11 is connected to the hydraulic push cylinder 10.

[0046] This application is applicable to the processing of stainless steel thin-walled bending pipes for the booster delivery system of launch vehicles, and mainly solves the problem that the length of the straight section is limited, and wrinkles, distortion and other defects are prone to occur during the existing processing of small bending radius pipes. Under the existing process constraints, this application combines push-bending forming with liquid filling forming technology. First, the inside of the pipe is filled and compacted by a rubber ball 8, and the force is evenly applied during the push-bending process. Then, pressurized bulging is achieved by filling liquid, and the surface of the bent pipe is molded and shaped.

[0047] R is the bending radius of the elbow, D is the outer diameter of the elbow, and L is the length of the straight segment.

[0048] The rubber ball 8 is filled inside the pipe, and the gap of the rubber ball 8 is filled with liquid to increase the overall support area inside the pipe, increase the rigidity of the straight section of the pipe, and effectively prevent instability and wrinkling during the bending process. The length L of the straight section is increased from 1D to 2-3D.

[0049] The inner cavity profile of the curved section of the guide sleeve 4 only includes the outer curved profile. The outer friction coefficient of the inner cavity profile of the guide sleeve 4 is 0.8, and the inner friction coefficient is 1.6, which produces differential lubrication. The inner cavity profile of the guide sleeve 4 is designed and arranged on the straight section and the outer side of the bend, and the roughness is processed to 0.8, which effectively reduces the friction coefficient of the straight section and the outer side of the pipe during the bending process, realizes differential friction, and increases the effective length of the straight section.

[0050] The guide sleeve 4 is fitted with the push-bending mold 5 . The inner cavity of the push-bending mold 5 includes a vertical section, a curved section and a horizontal section. The curved section of the guide sleeve 4 is smoothly connected with the horizontal section of the push-bending mold 5 .

[0051] The movable ball joint 11 extends inward from the horizontal section opening of the push-bending mold 5 to be connected with the straight pipe, and the diameter of the spherical end of the movable ball joint 11 matches the inner diameter of the guide sleeve 4.

[0052] The upper sealing member includes a sealing joint 6 and a sealing ring 7. The sealing joint 6 is arranged inside the upper end of the straight pipe. One or more sealing rings 7 are arranged around the sealing joint 6. The sealing joint 6 is sealed and connected to the straight pipe through the sealing ring 7.

[0053] A through hole is provided in the center of the sealing joint 6, and the hydraulic booster pipe 3 extends through the through hole into the straight pipe, and the hydraulic booster pipe 3 is interference fit with the through hole. The hydraulic booster 12 can linearly adjust the internal pressure P of the pipe to control the internal support force of the pipe during the bending process.

[0054] The lower sealing member comprises a rubber block which is installed inside the lower end of the straight pipe and is sealingly connected to the straight pipe.

[0055] The push rod 2 is fixedly mounted on the lower side of the upper table of the hydraulic press through the upper support plate 1.

[0056] A pressure sensor 9 is installed inside the movable ball joint 11, which can monitor and adjust the thrust force during the bending process in real time to control the bending deformation of the pipe during the bending process.

[0057] This application uses the method of "rubber ball 8 + hydraulic filling gap" to increase the support pressure inside the pipe, thereby increasing the rigidity of the straight section of the pipe, effectively preventing instability and wrinkling during the bending process, and increasing the straight section length L from 1D to 2-3D.

[0058] The present application reduces the friction coefficient of the straight section of the pipe by adopting the form of differential friction, differentially adjusts the friction coefficient of the inner and outer sides of the bend, increases the length of the straight section and achieves uniform force during the bending process.

[0059] The present application uses liquid filling to form, which can realize pressurized expansion of the pipe after push-bending by filling it with liquid. The structure of the rubber ball 8 is adopted, the filling effect is better, and it is not easy to produce a hanging area. The surface of the bent pipe is molded and shaped, which improves the mold accuracy of the part after forming, reduces the springback of the part, and realizes high-precision processing.

[0060] Example 2

[0061] Based on Example 1, Figure 4-7 As shown, a method for using a small bending radius pipe push bending device provided by the present invention comprises the following steps:

[0062] Step S1, fasten the push-bending mold 5 to the upper side of the lower table of the hydraulic press and fix it with a pressing plate; install the straight pipe to be processed in the push-bending mold 5 and fit it with the guide sleeve 4; install one end of the movable ball joint 11 at the lower mouth of the push-bending mold 5, fit it with the lower end of the straight pipe to be processed through a rubber block, and install the other end on the hydraulic push cylinder 10; install the pressure sensor 9 in the movable ball joint 11;

[0063] Step S2, filling a plurality of rubber balls 8 into the inner cavity of the straight pipe to be processed and compacting them; fastening the upper support plate 1 to the lower side of the upper table of the hydraulic press and fixing it with a pressing plate; fastening the upper end of the push rod 2 to the upper support plate 1, installing a sealing joint 6 at the lower end of the push rod 2, installing the sealing joint 6 at the upper end of the straight pipe to be processed, and fitting it tightly to the inner wall of the straight pipe through a sealing ring 7;

[0064] Step S3, inject water into the hydraulic booster pipe 3 through the hydraulic booster 12 to complete the filling of the inner cavity gap of the straight pipe to be processed, start the press to apply a preset downward force F to the push rod 2, and press down at a constant preset speed to set the filling pressure P 初始 Provide pressurized support inside the straight pipe;

[0065] Step S4, at the hydraulic pressure P 初始 With the support of , as the push rod 2 moves downward, the straight tube begins to bend and form; the movable ball joint 11 applies a push-out force to support the rubber ball 8 and the liquid inside the straight tube, and moves back with it; after the 90° bending is completed, the filling pressure P is gradually increased to pressurize and shape the inside of the straight tube; after the shaping is completed, the pressure P is unloaded, the rubber ball 8 and the formed bent pipe parts are taken out, and the processing process is completed.

[0066] The present application reduces circumferential and longitudinal welds through integral forming, thereby effectively improving product accuracy and reliability.

[0067] This application breaks through the manufacturing bottleneck of traditional processes under the constraints of "thin walls, small bending radius, and high dimensional accuracy", realizes the overall flexible processing of the catheter, eliminates 3 welds, and improves the dimensional accuracy from 2mm to 0.5mm, greatly improving product reliability.

[0068] The processing efficiency of this application can be improved by more than 40%, which can shorten the supply chain and development cycle. Based on the overall small bending radius elbow structure of this application, the traditional mode of aerospace product structural design and manufacturing has been changed, the production process has been greatly simplified, and the traditional catheter development and production process has been reduced from 14 to 7 times, shortening the supply chain and development cycle, speeding up the speed of parts production and system integration, and improving the processing efficiency by more than 40%, providing technical support for promoting the efficient development of aerospace model products.

[0069] This application integrates and applies a variety of advanced technical means, and solves the product structure design constrained by traditional manufacturing processes through flexible ideas, liberates design ideas and concepts, breaks the high dependence on existing process levels, and is a powerful measure to achieve overall high-reliability manufacturing.

[0070] The small bending radius tube integral forming device based on push-bending-hydraulic composite forming and the use method thereof of the present application, through the integrated innovation of configuration design and manufacturing process, breaks through the integral forming of long straight section tube of 1D bending radius of power duct, effectively reduces welds, improves product dimensional accuracy and efficiency, and achieves the research and development goals of lightweight and high performance. It breaks through the limitations of single manufacturing technology such as traditional manual work, and utilizes the composite forming technology combining push-bending manufacturing technology and liquid filling forming technology to achieve a breakthrough in the thin-wall bending process of aircraft, which has important application prospects in the future aircraft structure design and manufacturing.

[0071] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0072] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A small bending radius pipe push bending device, characterized in that: include: A push rod (2), a push-bending mold (5), a rubber ball (8), a hydraulic push cylinder (10), a movable ball joint (11) and a hydraulic booster (12); the push-bending mold (5) is installed on the lower table of the hydraulic press; a guide sleeve (4) is installed inside the push-bending mold (5); the guide sleeve (4) includes a vertical section and a curved section; a straight pipe to be processed is installed in the vertical section of the guide sleeve (4) and the two are arranged in close contact; and a plurality of the rubber balls (8) are filled in the straight pipe; The upper end of the push rod (2) is fixedly mounted on the lower side of the upper table of the hydraulic press, and the lower end of the push rod (2) extends into the guide sleeve (4) and is tightly abutted against the upper end of the straight pipe through an upper sealing member; The output end of the hydraulic booster (12) is connected to a hydraulic booster pipe (3), and the hydraulic booster pipe (3) passes through the upper sealing member and extends into the straight pipe; The spherical end of the movable ball joint (11) is tightly pressed against the lower end of the straight pipe via a lower sealing member, and the other end of the movable ball joint (11) is connected to the hydraulic jacking cylinder (10).

2. The small bending radius pipe push bending device according to claim 1, characterized in that: The inner cavity profile of the curved section of the guide sleeve (4) comprises only an outer curved profile, and the outer friction coefficient of the inner cavity profile of the guide sleeve (4) is 0.8, and the inner friction coefficient is 1.

6.

3. The small bending radius pipe push bending device according to claim 1, characterized in that: The guide sleeve (4) is fitted with the push-bending mold (5); the inner cavity of the push-bending mold (5) comprises a vertical section, a curved section and a horizontal section; the curved section of the guide sleeve (4) is smoothly connected with the horizontal section of the push-bending mold (5).

4. The small bending radius pipe push bending device according to claim 3, characterized in that: The movable ball joint (11) extends inward from the horizontal section opening of the push-bending mold (5) to connect with the straight pipe, and the diameter of the spherical end of the movable ball joint (11) matches the inner diameter of the guide sleeve (4).

5. The small bending radius pipe push bending device according to claim 1, characterized in that: The upper sealing component comprises a sealing joint (6) and a sealing ring (7); the sealing joint (6) is arranged inside the upper end of the straight pipe; one or more sealing rings (7) are arranged on the circumference of the sealing joint (6); and the sealing joint (6) is sealingly connected to the straight pipe via the sealing ring (7).

6. The small bending radius pipe push bending device according to claim 1, characterized in that: A through hole is provided at the center of the sealing joint (6), and the hydraulic boosting pipe (3) passes through the through hole and extends into the straight pipe, and the hydraulic boosting pipe (3) is interference-fitted with the through hole.

7. The small bending radius pipe push bending device according to claim 1, characterized in that: The lower sealing member comprises a rubber block, which is installed inside the lower end of the straight pipe and is sealed and connected to the straight pipe.

8. The small bending radius pipe push bending device according to claim 1, characterized in that: The push rod (2) is fixedly mounted on the lower side of the upper table of the hydraulic press via the upper support plate (1).

9. The small bending radius pipe push bending device according to claim 1, characterized in that: A pressure sensor (9) is installed inside the movable ball joint (11).

10. A method for using a small bending radius pipe push bending device, characterized in that: The small bending radius pipe push bending device applied to any one of claims 1 to 9 comprises the following steps: Step S1, installing the straight pipe to be processed in the push-bending mold (5), and fitting it with the guide sleeve (4), and installing the movable ball joint (11) at the lower opening of the push-bending mold (5); Step S2, filling a plurality of rubber balls (8) into the inner cavity of the straight tube to be processed and compacting the rubber balls, and installing the lower end of the push rod (2) on the upper end of the straight tube to be processed; Step S3, the hydraulic booster (12) injects water into the inner part of the straight pipe to be processed through the hydraulic booster pipe (3) to complete the filling of the inner cavity gap of the straight pipe to be processed, and the press machine is started to apply a preset downward force F to the push rod (2), and presses down at a constant preset speed, setting the filling pressure P 初始 Provide pressurized support inside the straight pipe; Step S4, at the hydraulic pressure P 初始 Under the support, as the push rod (2) moves downward, the straight tube begins to bend and form, the movable ball joint (11) applies a push-out force to support the rubber ball (8) and the liquid inside the straight tube, and moves backward with it. After the 90° bending is completed, the filling pressure is gradually increased to pressurize and shape the inside of the straight tube. After the shaping is completed, the pressure is unloaded, and the rubber ball (8) and the formed bent tube parts are taken out to complete the processing process.

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