A method for manufacturing a copper-nickel alloy press-fitting elbow

Abstract

The application provides a copper-nickel alloy clamp-pressing elbow manufacturing method, which comprises the following steps: S1: blanking: adopting copper-nickel alloy seamless pipe as a raw material, cutting the pipe to a specified size, removing burrs at the ends, and preparing a straight pipe; S2: bending: placing the cut straight pipe into a die of a pipe bender for bending to prepare a bent pipe; S3: machining: placing the bent pipe into a cutting machine to machine the two ends of the bent pipe to a specified size; S4: forming: forming the ends into bulges suitable for clamp pressing; S5: pipe fitting cleaning: performing oil dirt removal treatment on the elbow prepared in S4; S6: annealing treatment; and S7: polishing and grinding. The copper-nickel alloy clamp-pressing elbow manufacturing method successfully realizes the manufacturing of a copper-nickel alloy clamp-pressing elbow through the processes of blanking, pipe bending, end forming and heat treatment, has high efficiency, low cost, good surface quality and is suitable for batch production of copper-nickel alloy clamp-pressing elbows.

Description

Technical Field

[0001] This invention relates to the technical field of metal material processing and manufacturing methods, and in particular to a method for manufacturing copper-nickel alloy press-fit elbows. Background Technology

[0002] Pipe fittings are parts that connect pipes into pipelines. They play a role in connecting, controlling, changing direction, diverting flow, sealing, and supporting in piping systems. Commonly used elbow fittings are pipe fitting structures used to change the direction of the pipeline. Existing pipe fittings are generally two-section structures at both ends, used to place conventional sealing rings and metal rings respectively. After the pipe fittings are connected to the pipes, they are pressed together with the metal rings and sealing rings in close contact using a compression tool.

[0003] For pipeline components of seawater pipeline systems in ships and marine engineering, the corrosive properties and biofouling of seawater place high demands on the performance of materials and management connections.

[0004] Invention patent CN112917107A, "A Manufacturing Process for Stainless Steel Press-fit Equal Diameter Tees," describes a manufacturing process for stainless steel press-fit equal diameter tees. The manufacturing steps include: feeding, laser cutting, chamfering, hydroforming, punching, high-frequency heating, drawing, end finishing, pipe cleaning, bright solution annealing, polishing, installing sealing rings, and pipe testing. Invention patent CN100414159C, "Manufacturing Method for Press-fit Pipe Fittings," discloses a manufacturing method for threaded press-fit stainless steel pipe fittings. Specifically, it includes first precision casting of threaded parts, then extruding and forming the end portion using thin-walled pipe material, then connecting the two parts using friction welding, and finally precision machining. The existing technical solutions still mostly use stainless steel fasteners. Although those skilled in the art know that copper-nickel alloys have good resistance to seawater corrosion and marine biofouling, as well as excellent cold and hot working properties, when the structure of this material is widely used in the pipeline components of seawater pipeline systems in ships and marine engineering, it is mainly connected by welding or threading. Welding is relatively complicated and inefficient, while threaded connection is relatively expensive.

[0005] There are no publicly available reports on the manufacturing methods for copper-nickel alloy press-fit elbows, and China currently lacks the capacity for mass production of copper-nickel alloy press-fit pipe fittings. Summary of the Invention

[0006] In view of this, the present invention aims to propose a method for manufacturing copper-nickel alloy press-fit elbows to solve the problems of low connection efficiency and high cost of pipeline components in marine and ocean engineering seawater pipeline systems.

[0007] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0008] A method for manufacturing a copper-nickel alloy press-fit elbow includes the following steps:

[0009] S1: Cutting: Using seamless copper-nickel alloy tubing as raw material, with a wall thickness of 87.5% to 95% of the nominal wall thickness, the tubing is cut to the specified size, the end burrs are removed, and straight tubing is prepared.

[0010] S2: Pipe bending: Install the pipe bending mold and mandrel on the worktable of the pipe bending machine, and then put the cut straight pipe into the mold of the pipe bending machine for bending to prepare the pipe bending.

[0011] S3: Machining: Place the bent pipe into the cutting machine and machine both ends of the bent pipe to the specified dimensions. The machined bent pipe has straight sections at both ends. After machining, remove the burrs at the ends.

[0012] S4: Forming: Apply lubricant to the inner and outer surfaces of both ends of the bend, then place the bend into the mold of the bend forming machine to form the end into a bulge suitable for pressing;

[0013] S5: Pipe fitting cleaning: Remove oil and dirt from the elbows prepared in S4;

[0014] S6: Annealing treatment:

[0015] S7: Polishing and grinding.

[0016] Furthermore, in step S2, the bending radius of the pipe in the pipe bending process is R≈1.5D, where D is the outer diameter of the pipe, and the bending speed is 10°~15° / s.

[0017] Furthermore, in step S4, the end forming process of the bend is divided into two steps:

[0018] S41: The pipe end is expanded in two stepped sections. The inner diameter of the first section is expanded to a size suitable for pipe insertion, and the inner diameter of the second section is expanded to a size suitable for sealing ring insertion. The mold advance speed during this process is A mm / s.

[0019] S42: The second section of expanded pipe is bent into a bulge suitable for the placement of the sealing ring. The mold advance speed during this process is Bmm / s.

[0020] Where A > B.

[0021] Furthermore, the value range of A is 20 to 25, and the value range of B is 10 to 15.

[0022] Furthermore, in step S4, the lubricant is evenly applied to the inner and outer surfaces at both ends of the bend.

[0023] Furthermore, in step S6, during the annealing process, the elbow is placed in a vacuum heat treatment furnace for annealing, with a heating temperature of 700-780°C and a holding time of 30-45 minutes. After cooling to 200°C in the furnace, it is removed.

[0024] Furthermore, the hardness of the elbow end after annealing is less than 120HV5.

[0025] Furthermore, in step S7, the annealed copper-nickel alloy press-fit elbow is placed in a polishing machine, brown corundum abrasive is added, and fine polishing is performed.

[0026] Furthermore, in step S7, spherical brown corundum abrasive is selected, with an abrasive size of 12-25mm; the vibration frequency of the grinding machine is 20-40Hz / s, and the grinding time is 10-20min.

[0027] Furthermore, the prepared copper-nickel alloy press-fit elbows were used in low-pressure seawater pipeline systems.

[0028] Compared with existing technologies, the copper-nickel alloy press-fit elbow manufacturing method of the present invention has the following advantages:

[0029] (1) The copper-nickel alloy press-fit elbow manufacturing method of the present invention successfully realizes the manufacturing of copper-nickel alloy press-fit elbows through processes such as blanking, pipe bending, end forming, and heat treatment. It is efficient, low-cost, and has good surface quality, making it suitable for mass production of copper-nickel alloy press-fit elbows.

[0030] (2) The copper-nickel alloy press-fit elbow manufacturing method of the present invention uses the prepared copper-nickel alloy press-fit elbow in a low-pressure seawater pipeline system. By using thin-walled copper-nickel alloy pipes and press-fit fittings, the cost can be greatly reduced and the efficiency of seawater pipeline installation and construction can be significantly improved. Attached Figure Description

[0031] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0032] Figure 1 This is a schematic diagram of the bent pipe in an embodiment of the present invention;

[0033] Figure 2 This is a structural schematic diagram of the machined bent pipe in an embodiment of the present invention;

[0034] Figure 3 This is a schematic diagram of the forming process of the end of the pressure elbow in an embodiment of the present invention;

[0035] Figure 4This is a schematic diagram of the finished press-fit elbow in an embodiment of the present invention;

[0036] Figure 5 These are actual photos of the DN65-90° and DN80-90° press-fit elbows in the embodiments of the present invention;

[0037] Explanation of reference numerals in the attached figures:

[0038] First end 1, second end 2. Detailed Implementation

[0039] To make the technical means and objectives and effects of the present invention easier to understand, the embodiments of the present invention will be described in detail below with reference to specific illustrations.

[0040] It should be noted that all directional and positional terms used in this invention, such as "up," "down," "left," "right," "front," "back," "vertical," "horizontal," "inner," "outer," "top," "lower," "lateral," "longitudinal," and "center," are only used to explain the relative positional relationships and connections between components in a specific state (as shown in the accompanying drawings). They are merely for the convenience of describing the invention and do not require the invention to be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on the invention. Furthermore, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated.

[0041] In the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0042] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0043] like Figures 1-4 As shown, this invention discloses a method for manufacturing a copper-nickel alloy press-fit elbow, comprising the following steps:

[0044] S1: Cutting: Using seamless copper-nickel alloy tubing as raw material, with a wall thickness of 87.5-95% of the nominal wall thickness, the tubing is cut to the specified size, the end burrs are removed, and straight tubing is prepared.

[0045] S2: Pipe bending: Install the pipe bending mold and mandrel on the worktable of the pipe bending machine, and then put the cut straight pipe into the mold of the pipe bending machine for bending to prepare the pipe bending.

[0046] S3: Machining: Place the bent pipe into the cutting machine and machine both ends of the bent pipe to the specified dimensions. The machined bent pipe must have a certain length of straight section at both ends. After machining, remove the burrs at the ends.

[0047] S4: Forming: Apply lubricant to the inner and outer surfaces of both ends of the bend, then place the bend into the mold of the bend forming machine to form the end into a bulge suitable for pressing;

[0048] S5: Pipe fitting cleaning: Remove oil and dirt from the elbows prepared in S4;

[0049] S6: Annealing treatment:

[0050] S7: Polishing and grinding.

[0051] The present invention discloses a manufacturing process for a copper-nickel alloy press-fit elbow, which involves preparing a copper-nickel alloy press-fit elbow with a press-fit bulge from copper-nickel alloy pipe through blanking, pipe bending, machining, and forming steps. The elbow is then cleaned with an ultrasonic cleaner to remove oil and ensure a clean surface. Next, an annealing process is used to reduce the end hardness of the formed elbow, improving the reliability of press-fit deformation at the elbow end. Finally, the annealed elbow is polished to obtain a copper-nickel alloy press-fit elbow with good surface quality.

[0052] The copper-nickel alloy press-fit elbow manufacturing method of the present invention successfully realizes the manufacturing of copper-nickel alloy press-fit elbows through processes such as blanking, pipe bending, end forming, and heat treatment. It is efficient, low-cost, and produces good surface quality, making it suitable for mass production of copper-nickel alloy press-fit elbows.

[0053] As a preferred example of the present invention, in step S2, the bending radius of the pipe in the pipe bending process is R≈1.5D, where D is the outer diameter of the pipe, and the bending speed is 10°~15° / s.

[0054] The raw material used for pipe bending is negative tolerance tubing, resulting in lighter fittings. Furthermore, the thinning of the back arc during bending does not exceed 5%, still meeting usage requirements. This design prevents stress concentration or abrupt changes in the performance of seamless copper-nickel alloy tubing during bending, ensuring stable product quality and performance.

[0055] As a preferred example of the present invention, in step S4, the end forming process of the bent tube is divided into two steps:

[0056] S41: The pipe end is expanded in two stepped sections. The inner diameter of the first section is expanded to a size suitable for pipe insertion, and the inner diameter of the second section is expanded to a size suitable for sealing ring insertion. The mold advance speed during this process is A mm / s.

[0057] S42: The second section of expanded pipe is bent into a bulge suitable for the placement of the sealing ring. The mold advance speed during this process is Bmm / s.

[0058] Where A > B.

[0059] As a preferred example of the present invention, the value of A is in the range of 20 to 25, and the value of B is in the range of 10 to 15.

[0060] Because the expanded material undergoes work hardening, its strength increases while its elongation decreases. Therefore, the deformation rate needs to be reduced during the forming bulge process to ensure a high yield. The wall thickness at the end of the fitting is not less than the original pipe wall thickness. This design ensures the reliability of the press-fit structure fabricated after bending the copper-nickel alloy pipe.

[0061] As a preferred example of the present invention, in step S4, the lubricant is evenly applied to the inner and outer surfaces of both ends of the bend.

[0062] This setup further improves the smoothness and stability of preparing the clamping bulge at the end of the copper-nickel alloy bend.

[0063] As a preferred example of the present invention, in step S6, during the annealing process, the elbow is placed in a vacuum heat treatment furnace for annealing, the heating temperature is 700-780°C, the holding time is 30-45 minutes, and it is taken out after being cooled to 200°C in the furnace.

[0064] As a preferred example of the present invention, the hardness of the elbow end after annealing is less than 120HV5.

[0065] After annealing, the hardness and elongation of the elbow end match those of the original pipe material, making it more conducive to press-fit connections. This feature further improves the stability and ease of assembly of the press-fit connection of the copper-nickel alloy elbow.

[0066] As a preferred example of the present invention, in step S7, the annealed copper-nickel alloy press-fit elbow is placed in a polishing machine, brown corundum abrasive is added, and fine polishing is performed.

[0067] Specifically, in step S7, spherical brown corundum abrasive is selected, with an abrasive size of 12-25mm; the vibration frequency of the grinding machine is 20-40Hz / s, and the grinding time is 10-20min.

[0068] As a preferred example of the present invention, in step S1, a fully automatic laser-cut copper-nickel alloy seamless tube is used, with a blanking length of 4D to 8D. In step S2, the distance from the center of the first end 1 to the center of the second end 2 of the processed bent tube is L, and the distance from the center of the second end 2 to the center of the first end 1 of the bent tube is L. The value of L ranges from 2.5D to 3.5D. In step S4, when forming the end of the bent tube, the end of the tube is expanded in two steps. The inner diameter of the first step is expanded to 1.01D to 1.02D, and the length of the first step expansion is 0.5D to 0.7D. The inner diameter of the second step is expanded to 1.1D to 1.3D, and the length of the first step expansion is 0.25D to 0.35D. The bulge bending radius on the tube after the second step expansion is 5.3 to 6mm. The length H of the tube that can be inserted into the end is not less than 0.7D. Preferably, the length H of the tube inserted into the bent tube is 0.75D to 1.0D.

[0069] The bulge bending radius on the second section of expanded pipe is 3-10mm. This design allows the copper-nickel alloy press-fit elbow to be used in different specifications, further improving the surface quality of the copper-nickel alloy press-fit elbow after processing and ensuring the stability and reliability of the assembly connection during use.

[0070] As a preferred example of the present invention, the method for manufacturing copper-nickel alloy press-fit elbows describes the use of the prepared copper-nickel alloy press-fit elbows in low-pressure seawater pipeline systems with pipeline specifications ranging from DN12 to DN100 and a burst pressure of not less than 6.4 MPa, i.e., not less than 4 times the nominal pressure. Using thin-walled copper-nickel alloy pipes and press-fit fittings can significantly reduce costs and substantially improve the efficiency of seawater pipeline installation.

[0071] Example 1

[0072] This invention has been applied to the manufacture of copper-nickel alloy DN65-90° press-fit elbows, as detailed below:

[0073] 1) Φ76.1x2 copper-nickel alloy seamless pipe is selected and fully automatic laser cutting is used to cut the pipe. The cutting length is 360±2mm. After cutting, the end burrs are removed.

[0074] 2) Install the DN65 pipe bending mold and mandrel on the worktable of the pipe bending machine, and then put the cut straight pipe into the mold of the pipe bending machine for bending. The bending angle is 90°, the bending radius R = 115mm, and the bending speed is 12° / s.

[0075] 3) Place the bent pipe into the cutting machine for machining. After machining, the distance from the center of the first end 1 to the center of the second end 2 of the bent pipe is L, and the distance from the center of the second end 2 to the center of the first end 1 of the bent pipe is also L. L = 175 ± 1 mm. Remove the end burrs.

[0076] 4) Apply lubricant evenly to the inner and outer surfaces of the straight sections at both ends of the bend. Then, place the bend into the mold of the bend forming machine to form the end into a bulge suitable for clamping. The end forming process consists of two steps: 1) Expanding the pipe: Expand the pipe end in two stepped sections. The first section expands the inner diameter to Φ77.3±0.2mm and the length to 42±0.3mm. The second section expands the inner diameter to Φ91.6±0.3mm and the length to 18±0.3mm. The mold advancing speed during this process is 20mm / s. 2) Bending the pipe after the second expansion section into a bulge suitable for placing the sealing ring. The bending radius at the bulge is 4.8~5.5mm. The mold advancing speed during this process is 12mm / s. After forming, the length of the pipe that can be inserted into the end is 55±1.5mm.

[0077] 5) Pipe cleaning: Place the elbow into an ultrasonic cleaner to remove oil and dirt;

[0078] 6) Annealing treatment: The hardness and plasticity of the elbow end will increase after forming, which is not conducive to the clamping deformation of the elbow, so annealing treatment is required. The elbow is placed in a vacuum heat treatment furnace for annealing at a heating temperature of 720±10℃ and a holding time of 35 minutes. After cooling to 200℃ in the furnace, it is removed. The hardness of the elbow end after annealing is 100HV5.

[0079] 7) Place the annealed copper-nickel alloy press-fit elbow into a grinding machine, add brown fused alumina abrasive, and perform fine polishing. Use spherical brown fused alumina abrasive with a size of 20mm; the grinding machine vibration frequency is 30Hz / s, and the grinding time is 15 minutes. After polishing, the finished copper-nickel alloy press-fit elbow is obtained, with a smooth, clean, and defect-free surface.

[0080] Example 2:

[0081] This invention has been applied to the manufacture of copper-nickel alloy DN80-90° press-fit elbows, as detailed below:

[0082] 1) Φ88.9x2 copper-nickel alloy pipe is selected and fully automatic laser cutting is used to cut the pipe. The cutting length is 430±3mm. After cutting, the end burrs are removed.

[0083] 2) Install the DN80 pipe bending mold and mandrel on the worktable of the pipe bending machine, and then put the cut straight pipe into the mold of the pipe bending machine for bending. The bending angle is 90°, the bending radius R = 135mm, and the bending speed is 10° / s.

[0084] 3) Place the bent pipe into the cutting machine for processing. After processing, the distance from one end of the bent pipe to the center of the other end is L = 204 ± 1 mm. Remove the burrs from the ends.

[0085] 4) Apply lubricant evenly to the inner and outer surfaces of the straight sections at both ends of the bend. Then, place the bend into the mold of the bend forming machine to form the end into a bulge suitable for clamping. The end forming process consists of two steps: 1) Expanding the pipe: Expand the pipe end in two stepped sections. The first section expands the inner diameter to Φ91.3±0.2mm and the length to 50±0.3mm. The second section expands the inner diameter to Φ106.3±0.3mm and the length to 19±0.3mm. The mold advancing speed during this process is 20mm / s. 2) Bending the pipe after the second expansion section into a bulge suitable for placing the sealing ring. The bending radius at the bulge is 5.3~6mm. The mold advancing speed during this process is 10mm / s. After forming, the length of the pipe that can be inserted into the end is 63±1.5mm.

[0086] 5) Pipe cleaning: Place the elbow into an ultrasonic cleaner to remove oil and dirt;

[0087] 6) Annealing treatment: The hardness and plasticity of the elbow end will increase after forming, which is not conducive to the clamping deformation of the elbow, so annealing treatment is required. The elbow is placed in a vacuum heat treatment furnace for annealing. The heating temperature is 740±10℃, the holding time is 40min, and it is removed after cooling to 200℃ in the furnace. The hardness of the elbow end after annealing is 95HV5;

[0088] 7) Place the annealed copper-nickel alloy press-fit elbow into a grinding machine, add brown fused alumina abrasive, and perform fine polishing. Use spherical brown fused alumina abrasive with a size of 20mm; the grinding machine vibration frequency is 30Hz / s, and the grinding time is 20 minutes. After polishing, the finished copper-nickel alloy press-fit elbow is obtained, with a smooth, clean, and defect-free surface.

[0089] The actual press-fit elbows prepared in Examples 1 and 2 are shown below. Figure 5 As shown.

[0090] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for manufacturing a copper-nickel alloy press-fit elbow, characterized in that, Includes the following steps: S1: Cutting: Using seamless copper-nickel alloy tubing as raw material, with a wall thickness of 87.5% to 95% of the nominal wall thickness, the tubing is cut to the specified size, the end burrs are removed, and straight tubing is prepared. S2: Pipe bending: Install the pipe bending mold and mandrel on the worktable of the pipe bending machine, and then put the cut straight pipe into the mold of the pipe bending machine for bending to prepare the pipe bending. S3: Machining: Place the bent pipe into the cutting machine and machine both ends of the bent pipe to the specified dimensions. The machined bent pipe has straight sections at both ends. After machining, remove the burrs at the ends. S4: Forming: Apply lubricant to the inner and outer surfaces of both ends of the bend, then place the bend into the mold of the bend forming machine to form the end into a bulge suitable for pressing. The end forming process of the bend is divided into two steps: S41: The pipe end is expanded in two stepped sections. The inner diameter of the first section is expanded to a size suitable for pipe insertion, and the inner diameter of the second section is expanded to a size suitable for sealing ring insertion. The mold advance speed during this process is A mm / s. S42: The second section of expanded pipe is bent into a bulge suitable for the placement of the sealing ring. The mold advance speed during this process is B mm / s, where A > B. S5: Pipe fitting cleaning: Remove oil and dirt from the elbows prepared in S4; S6: Annealing treatment: During the annealing treatment, the elbow is placed in a vacuum heat treatment furnace for annealing. The heating temperature is 700-780℃, the holding time is 30-45min, and it is taken out after cooling to 200℃ in the furnace. The hardness of the elbow end after annealing treatment is less than 120HV5. S7: Polishing and grinding, the burst pressure of the copper-nickel alloy press-fit elbow is not less than 6.4MPa.

2. The method for manufacturing a copper-nickel alloy press-fit elbow according to claim 1, characterized in that, In step S2, the bending radius of the pipe in the pipe bending process is R≈1.5D, where D is the outer diameter of the pipe, and the bending speed is 10°~15° / s.

3. The method for manufacturing a copper-nickel alloy press-fit elbow according to claim 1, characterized in that, The value of A ranges from 20 to 25, and the value of B ranges from 10 to 15.

4. The method for manufacturing a copper-nickel alloy press-fit elbow according to claim 1, characterized in that, In step S4, the lubricant is evenly applied to the inner and outer surfaces of both ends of the bend.

5. The method for manufacturing a copper-nickel alloy press-fit elbow according to claim 1, characterized in that, In step S7, the annealed copper-nickel alloy press-fit elbow is placed in a polishing machine, brown corundum abrasive is added, and fine polishing is performed.

6. The method for manufacturing a copper-nickel alloy press-fit elbow according to claim 5, characterized in that, In step S7, spherical brown corundum abrasive is selected, with an abrasive size of 12-25mm; the vibration frequency of the grinding machine is 20-40Hz / s, and the grinding time is 10-20min.

7. The method for manufacturing a copper-nickel alloy press-fit elbow according to claim 2, characterized in that, The prepared copper-nickel alloy press-fit elbow was used in a low-pressure seawater pipeline system.

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