A method for forming a liquid-filled protrusion in a large aspect ratio multi-pass tube
The liquid-filled protrusion forming method solved the forming problem of multi-port pipes with large diameter-to-thickness ratio, achieved high-quality forming of complex pipes, avoided defects such as wrinkling and thinning, and improved production efficiency and forming accuracy.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SICHUAN AEROSPACE LONG MARCH EQUIP MFG CO LTD
- Filing Date
- 2023-10-31
- Publication Date
- 2026-06-02
AI Technical Summary
Large diameter-to-thickness multi-port pipes are prone to defects such as wrinkling, excessive thinning, cracking, cross-sectional distortion, and unloading springback during the forming process. Traditional forming processes are difficult to produce complex pipe fittings such as variable cross-section pipe fittings and axially bent pipe fittings.
The liquid-filled protrusion forming method is adopted. By filling the tube blank with liquid medium and applying internal pressure, the liquid pressure is used to push the protrusion mold to form the tube. Combined with pre-expansion forming, pre-drilled hole opening and sealing tie rod technology, the overall forming of large diameter-to-thickness multi-port tubes can be achieved.
It effectively avoids forming defects, improves forming quality and precision, shortens the production cycle, reduces production costs, and is suitable for mass production of complex pipe fittings.
Smart Images
Figure CN117444036B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of multi-port tube forming technology, specifically to a method for forming liquid-filled protrusions in multi-port tubes with a large diameter-to-thickness ratio. Background Technology
[0002] Multi-way pipes are crucial components of aerospace piping systems. Their structural forms include tees and crosses, with tees being the most widely used. Based on shape, they can be categorized as T-type, Y-type, and U-type tees, and based on diameter, they can be classified as equal-diameter tees and reducing tees. As aerospace structural components trend towards lightweight and integrated designs, the manufacturing method for multi-way pipes is shifting from traditional welding to integral forming. High diameter-to-thickness (outer diameter / thickness) multi-way pipes, due to their hollow internal structure, offer advantages such as lightweight, low consumption, and excellent structural performance, leading to their wider application. However, a larger diameter-to-thickness ratio increases forming difficulty, making them highly susceptible to defects such as wrinkling, excessive thinning, cracking, cross-sectional distortion, and unloading springback, with wrinkling being particularly severe. Furthermore, complex pipe fittings, such as variable cross-section fittings and axially bent fittings, are difficult to form and cannot be produced using traditional forming processes alone. Summary of the Invention
[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for forming liquid-filled protrusions in multi-channel pipes with a large diameter-to-thickness ratio.
[0004] To achieve the above objectives, the present invention employs the following technical solutions:
[0005] A method for forming a liquid-filled protrusion in a multi-port pipe with a large diameter-to-thickness ratio includes the following steps:
[0006] A. Pre-expansion: Install the upper and lower molds, and close them together using a hydraulic press. Fill the target position on the tube blank with liquid to expand and shape the part to be bulged into a bulge.
[0007] B. Pre-drilling holes: Use a laser cutting machine to drill pre-drilled holes at the bulging position of the tube blank;
[0008] C. Install the punching die: Install the punching die and sealing tie rod. Place the punching die inside the tube blank. The top of the punching die has a threaded hole for connecting the sealing tie rod.
[0009] D. Sealing: The lower end of the sealing rod is connected to the protrusion mold to provide loading force for protrusion forming. The upper end of the sealing rod forms a seal with the branch pipe groove through the sealing ring. The remaining outlets of the tube blank are respectively fitted with plugs and sealing rings to complete the sealing, thereby forming a closed cavity.
[0010] E. Liquid-filled protrusion: The plug is equipped with a liquid channel, which is connected to the inlet and outlet of the liquid-filling forming equipment to fill the tube blank with liquid, remove the gas inside the tube blank, check the overall sealing performance, and after the seal is qualified, gradually increase the pressure of the liquid chamber. The pressure difference between the inner and outer sides of the sealing rod drives the protrusion mold to move outward, thus completing the protrusion forming process.
[0011] As a preferred embodiment, the height of the punch mold does not exceed the diameter of the tube blank.
[0012] In a preferred embodiment, in step A, the position of the pre-expansion is determined by the position of the target branch pipe.
[0013] As a preferred embodiment, in step B, the size of the pre-drilled hole depends on the diameter of the target branch pipe and the flange height.
[0014] The punch mold can be designed in different shapes according to the requirements of the formed parts. When the mold cavity is a straight tube, it can be used to form T-shaped tee pipes. When the mold cavity is a bent tube, it can be used to form Y-shaped or U-shaped tee pipes. When the mold cavity is a tee pipe, it can be used to form four-way pipes and reducing pipe fittings.
[0015] Liquid forming technology has significant advantages in processing large diameter-to-thickness pipes and irregularly shaped pipes. This technology uses high-pressure liquid as support, and the liquid pressure acts perpendicularly to the pipe surface and is the same in all directions. This ensures forming quality and prevents defects, thus improving the forming limit of the material. Liquid forming technology can also be combined with processes such as punching, bending, and stamping. With the help of special dies and molds, it can achieve the overall precise forming of complex-shaped parts, improving quality performance and production efficiency. The die structure is simple, suitable for mass production, and can effectively reduce production costs.
[0016] This invention combines liquid filling forming process with hole punching process, and designs a liquid filling hole punching method for multi-port pipes with large diameter-to-thickness ratio. This process requires filling the inside of the workpiece with liquid medium, applying and maintaining a certain internal pressure as a soft mold support, and then using liquid pressure to push the hole punching mold to achieve branch pipe forming. This method can effectively avoid various quality defects in the forming of multi-port pipes with large diameter-to-thickness ratio.
[0017] The present invention has the following advantages:
[0018] The method for forming large diameter-to-thickness multi-port pipes with liquid filling provided by this invention can realize the production of complex pipes such as variable cross-section pipes and axially bent pipes, effectively improving the forming quality of large diameter-to-thickness multi-port pipes. Since there is high-pressure liquid support inside the pipe blank during the convex hole process, it can effectively avoid quality defects such as hole distortion, wrinkling, poor mold adhesion, large springback, and poor forming accuracy. It is easy to operate, shortens the production cycle, and reduces production costs. Attached Figure Description
[0019] Figure 1 This is a schematic diagram of the lower and upper mold assembly.
[0020] Figure 2 This is a schematic diagram of the pre-expansion assembly.
[0021] Figure 3 This is a schematic diagram of the assembly after pre-expansion forming;
[0022] Figure 4 This is a schematic diagram of the assembly before filling the protrusion.
[0023] In the diagram: 1. Plug, 2. Outlet, 3. Pipe fitting, 4. High-pressure liquid, 5. Lower mold, 6. Sealing rod, 7. Pulley mold, 8. Sealing ring, 9. Inlet, 10. Upper mold. Detailed Implementation
[0024] The present invention will now be described in detail with reference to the accompanying drawings.
[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0026] Example 1:
[0027] Target tee dimensions: Y-type oblique tee, branch pipe diameter Φ145mm, transition section R30 with main pipe, height 8.29mm, branch pipe axis at 30.8° to the left end face of main pipe.
[0028] Tube blank dimensions: The blank is a Φ225mm×2.5mm bent pipe with a bending angle of 57.5°, a neutral layer bending radius of 220mm, and straight sections of 200mm at both ends.
[0029] Step 1. Pre-expansion
[0030] For mold trial assembly, first install the upper mold 10 and the lower mold 5, and ensure precise mold closing by using guide pillars. The gap between the upper and lower molds is less than 1mm. Separate the upper and lower molds along the Z-axis.
[0031] Install plugs 1 and sealing rings 8 at the left and right ends of the tube blank 3 respectively to form a sealing structure, thereby forming a closed cavity;
[0032] The left plug 1 is connected to the outlet 2 of the liquid filling forming equipment, and the right plug 1 is connected to the inlet 9 of the liquid filling forming equipment. Then, the upper and lower molds are closed to fill the inside of the pipe with emulsion, remove the gas inside the pipe blank, check the sealing performance of the mold to ensure that the liquid does not leak. After the seal is qualified, the pressure of the liquid chamber is gradually increased to 10MPa for pre-expansion forming.
[0033] Step 2. Drill pre-drilled holes
[0034] A laser cutting machine is used to make pre-drilled holes in the bulging part of the tube blank, with a pre-drilled hole diameter of Φ100mm;
[0035] Step 3. Mold Installation
[0036] Install the protruding hole mold 7 and the sealing tie rod 6. Place the protruding hole mold 7 inside the tube blank with the small end face facing out of the pre-made hole. Connect the protruding hole mold 7 and the sealing tie rod 6 with threads and tighten them.
[0037] Step 4. Seal
[0038] The upper end of the sealing rod 6 forms a seal with the groove of the mold support pipe through the sealing ring 8. The other two outlets of the pipe are respectively equipped with plugs 1 and sealing rings 8 to form a sealing structure, thereby forming a closed cavity.
[0039] Step 5. Filling protrusion
[0040] The left plug 1 is connected to the outlet 2 of the liquid filling forming equipment, and the right plug 1 is connected to the inlet 9 of the liquid filling forming equipment. The pipe is filled with emulsion to remove the gas inside the pipe blank. The sealing performance of the mold is checked to ensure that the liquid does not leak. After the seal is qualified, the pressure in the liquid chamber is gradually increased to 10MPa. The pressure difference between the inside and outside of the sealing rod 6 drives the punch mold 7 to move outward. The sealing rod 6 moves to the limiting device on the mold, thus completing the punch forming process.
[0041] This invention is not limited to the specific embodiments described above. The invention extends to any new feature or combination disclosed in this specification, as well as any new method or process step or combination disclosed herein.
Claims
1. A method for forming liquid-filled protrusions in a multi-channel pipe with a large diameter-to-thickness ratio, characterized in that, Includes the following steps: A. Pre-expansion: Install the upper and lower molds, and use a hydraulic press to close the mold to form a mold cavity. Fill the target position of the tube blank with liquid and expand it to form a bulge in the part to be convex. B. Pre-drilling holes: Use a laser cutting machine to drill pre-drilled holes at the bulging position of the tube blank; C. Install the punching die: Install the punching die and sealing tie rod. Place the punching die inside the tube blank. The top of the punching die has a threaded hole for connecting the sealing tie rod. D. Sealing: The lower end of the sealing rod is connected to the protruding die, and the upper end of the sealing rod forms a seal with the groove of the lower die branch pipe through the sealing ring. The remaining outlets of the tube blank are respectively fitted with plugs and sealing rings to complete the sealing, thereby forming a closed cavity. E. Liquid-filled protrusion: The plug is equipped with a liquid channel, which is connected to the inlet and outlet of the liquid-filling forming equipment to fill the tube blank with liquid, remove the gas inside the tube blank, check the overall sealing performance, and after the seal is qualified, gradually increase the pressure of the liquid chamber. The pressure difference between the inner and outer sides of the sealing rod drives the protrusion mold to move outward, thus completing the protrusion forming process.
2. The method for forming liquid-filled protrusions in a multi-channel pipe with a large diameter-to-thickness ratio according to claim 1, characterized in that: The height of the punch mold shall not exceed the diameter of the tube blank.
3. The method for forming liquid-filled protrusions in a multi-channel pipe with a large diameter-to-thickness ratio according to claim 1, characterized in that: In step A, the position of the pre-expansion is determined by the position of the target branch pipe.
4. The method for forming liquid-filled protrusions in a multi-channel pipe with a large diameter-to-thickness ratio according to claim 1, characterized in that: In step B, the size of the pre-drilled hole depends on the diameter of the target branch pipe and the flange height.
5. The method for forming a liquid-filled protrusion in a multi-channel pipe with a large diameter-to-thickness ratio according to claim 1, characterized in that: The punch mold can be designed in different shapes according to the requirements of the formed parts. When the mold cavity is a straight tube, it can be used to form T-shaped tee pipes. When the mold cavity is a bent tube, it can be used to form Y-shaped or U-shaped tee pipes. When the mold cavity is a tee pipe, it can be used to form four-way pipes and reducing pipe fittings.