Method of manufacturing a threaded copper-nickel alloy press-fit ferrule

Abstract

The application provides a threaded copper-nickel alloy compression type sleeve manufacturing method. The sleeve prepared by the method is composed of a compression type pipe fitting and a threaded pipe fitting, a weld seam is formed at the joint of the compression type pipe fitting and the threaded pipe fitting, and the method comprises the following steps: step one, preparing the compression type pipe fitting through a compression type pipe fitting forming machine; step two, preparing the threaded pipe fitting and pre-processing the threaded pipe fitting; step three, welding: welding the compression type pipe fitting and the threaded pipe fitting into a shape; step four, nondestructive testing: testing the weld seam; and step five, machining to obtain a finished compression type sleeve. The threaded copper-nickel alloy compression type sleeve manufacturing method is advantageous in simplifying the production process of the copper-nickel alloy compression type sleeve, improving the quality and dimensional accuracy of each end of the copper-nickel alloy compression type sleeve, enhancing the production efficiency of the compression type sleeve, improving the reliability and stability of the sleeve, and realizing mass production of the sleeve.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal material processing, in particular to a threaded copper-nickel alloy clamp-press type sleeve manufacturing method. BACKGROUND

[0002] At present, copper-nickel alloy BFe10-1.6-1 has excellent mechanical properties and matching corrosion resistance, and is widely used in marine engineering, ship and other fields of seawater pipeline system; in these fields, pipeline is essential, and the connecting pipe between the pipelines is a threaded clamp-press type sleeve, which is a non-standard product connected to the pipe at one end and to the thread at the other end. The conventional stainless steel clamp-press type pipe fitting in the prior art adopts argon arc welding, but the argon arc welding of the threaded stainless steel clamp-press type pipe fitting causes long welding time, long high-temperature residence time in the weld zone and the near weld zone, and thus easily causes micro-chemical segregation in the weld zone, so that the stainless steel clamp-press type pipe fitting cannot be used in harsh environments or for conveying corrosive liquids. In addition, the quality of the argon arc welded joint is easily affected by welding process, welding equipment, gas protection, welding worker's technical level and other conditions, the product quality is unstable, and due to the differences between stainless steel and copper-nickel alloy in price, hardness, acid resistance, welding performance and thermal conductivity, the production process and quality control of the steel sleeve cannot meet the production of copper-nickel alloy sleeve. Therefore, it is of great significance to study how to improve the production process of copper-nickel alloy sleeve.

[0003] In their article "Forming Process of Stainless Steel Press-fit Pipe Fittings" published in the 6th issue of *Metal Forming Technology* in 2003, Zhou Xiayu and Zhao Lijun introduced a forming process for thin-walled stainless steel press-fit tee fittings, including: blanking, tee extrusion, cap cutting, end flattening, end forming, welding, weld seam and surface treatment; welding is performed using wire-free argon arc welding; the basic procedure is to first align the two openings to be welded to the parts, and then spot weld two points in a 180° circumferential direction at the outer diameter joint to join the two parts together, which improves the effectiveness of welding to a certain extent. However, the quality of the argon arc weld joint is easily affected by the welding process, welding equipment, gas protection, and the skill level of the welder. Due to the influence of equal conditions, the product quality is more unstable. In the invention patent CN100414159C "Manufacturing Method of Press-fit Pipe Fittings", a method for manufacturing threaded press-fit stainless steel pipe fittings is disclosed. Specifically, the threaded parts are first manufactured using traditional precision casting process, then the end part is extruded and formed using thin-walled pipe material, then the two parts are connected by friction welding, and finally precision machining is performed. Friction welding is used to replace argon arc welding, which avoids the inability of steel sleeves after argon arc welding to effectively adapt to harsh environments or transporting corrosive liquids. However, the production process and quality control of steel sleeves cannot meet the requirements for the production of copper-nickel alloy sleeves. Summary of the Invention

[0004] In view of this, the present invention aims to propose a manufacturing method for threaded copper-nickel alloy press-fit sleeves, in order to solve the problem in the prior art that the production process of steel press-fit sleeves cannot meet the requirements of the production process of copper-nickel alloy press-fit sleeves due to the difference in properties between stainless steel and copper-nickel alloys. This simplifies the production process of copper-nickel alloy press-fit sleeves, improves the quality and dimensional accuracy of each end of the sleeves, enhances the production efficiency of press-fit sleeves, improves the reliability and stability of the sleeves, and enables mass production of the sleeves.

[0005] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0006] This invention relates to a method for manufacturing a threaded copper-nickel alloy press-fit sleeve, comprising the method producing a sleeve composed of a press-fit fitting and a threaded fitting welded together, wherein a weld is formed at the connection between the press-fit fitting and the threaded fitting, and the method includes the following steps:

[0007] Step 1: Prepare press-fit pipe fittings using a press-fit pipe fitting forming machine;

[0008] Step 2: Prepare threaded pipe fittings and pre-process them;

[0009] Step 3: Welding: Weld the press-fit fittings to the threaded fittings to form the shape;

[0010] Step 4: Non-destructive testing: Inspect the weld.

[0011] Step 5: Machining to obtain the finished press-fit sleeve.

[0012] Furthermore, step one includes:

[0013] Step S11: Cutting: Using seamless copper-nickel alloy tubing as raw material, cut the tubing to the first specified size and remove the burrs from both ends of the tubing;

[0014] Step S12: Forming: Apply stretching oil to both the inner and outer sides of both ends of the pipe, and prepare the pipe into a press-fit pipe using a conventional press-fit pipe forming machine;

[0015] Step S13: Wire cutting: The two ends of the press-fit tube are cut by wire cutting to form two press-fit fittings. Both press-fit fittings can be used with threaded fittings for welding sleeves.

[0016] Step S14: Pipe cleaning: Place the two press-fit pipe fittings into an ultrasonic cleaner to remove oil and dirt;

[0017] Step S15: Annealing treatment: Anneal the two formed press-fit pipe fittings and then proceed to step two.

[0018] Furthermore, step S15 includes: annealing the two formed press-fit pipe fittings, placing both press-fit pipe fittings into a nitrogen-protected furnace for annealing, and keeping the press-fit pipe fittings at a constant temperature during the annealing process by heating the furnace with the pipe fittings, and removing the press-fit pipe fittings when the furnace cools the press-fit pipe fittings to a first preset temperature T1.

[0019] Furthermore, during the annealing of press-fit pipe fittings, the heating temperature of the nitrogen-protected furnace is 700℃-780℃, and the holding time during furnace heating is 30min-45min; after annealing, the hardness of both ends of the press-fit pipe fittings is <120HV5.

[0020] Furthermore, step two includes:

[0021] Step S21: Material cutting: Using copper-nickel alloy ingots as raw materials, cut the ingots according to the second specification dimensions;

[0022] Step S22: Forging: After heating and holding the copper-nickel alloy ingot in an electric furnace, the ingot is forged into a semi-finished threaded pipe forging with a target outer diameter of R1.

[0023] Step S23: Non-destructive testing: Perform ultrasonic testing on the semi-finished forgings and determine whether they are qualified based on the test results. If yes, proceed to step S24; otherwise, return to step S22.

[0024] Step S24: Pre-processing: Perform finishing on the semi-finished forging and then proceed to step three.

[0025] Furthermore, in step S22, the electric furnace heating temperature is 920℃-960℃, the holding time is 30min-60min, the ingot forging adopts free forging method, and the final forging temperature is ≥ the second preset temperature T2.

[0026] Furthermore, step S24 includes:

[0027] Step S241: Perform precision machining on the welding end of the semi-finished forging of the threaded pipe fitting, wherein the machining length of the welding end of the semi-finished forging is the same as the machining length of the welding end of the press-fit pipe fitting.

[0028] Step S242: Pre-machine the outer diameter of the threaded end of the semi-finished forging;

[0029] Step S243: Determine whether the inner diameter r1 of the semi-finished forging is less than the first preset inner diameter value r0. If yes, proceed to step S244; otherwise, proceed to step S245.

[0030] Step S244: Select whether to perform internal diameter machining. If yes, proceed to step S245; otherwise, proceed to step three.

[0031] Step S245: Pre-machine the inner diameter of the threaded end of the semi-finished forging and then proceed to step three.

[0032] Furthermore, step three includes:

[0033] Step S31: Preparation before welding: Remove surface impurities from the welding ends of press-fit pipe fittings and threaded pipe fittings respectively;

[0034] Step S32: Assemble press-fit and threaded fittings: Connect the press-fit and threaded fittings to the welding workbench using the matching tools, and teach the laser.

[0035] Step S33: Welding and fixing: After completing the assembly of the press-fit pipe fitting and the threaded pipe fitting, the welding ends of the press-fit pipe fitting and the threaded pipe fitting are positioned and fixed by welding to form a weld, and the inner side of the weld is filled with protective gas.

[0036] Step S34: Weld according to the welding process flow to obtain a semi-finished press-fit sleeve;

[0037] Step S35: After welding is completed, check the surface quality of the weld of the semi-finished press-fit sleeve.

[0038] Furthermore, step four includes:

[0039] Step S41: Non-destructive testing: Perform radiographic testing on the weld and determine whether the radiographic testing results meet the requirements of NB / T47013.2 Class II. If yes, proceed to step S42; otherwise, return to step three.

[0040] Step S42: Perform penetrant testing on the weld and determine whether the penetrant test results meet the requirements of NB / T47013.5 Class I. If yes, proceed to step five; otherwise, return to step three.

[0041] Furthermore, in step five, the semi-finished press-fit sleeve that has passed non-destructive testing is precision machined according to the drawings to obtain the finished press-fit sleeve. The precision machining includes machining threads on the semi-finished press-fit sleeve.

[0042] Compared with the prior art, the method for manufacturing a threaded copper-nickel alloy press-fit sleeve according to the present invention has the following advantages:

[0043] Through processes such as blanking, forging, pre-processing, end forming, heat treatment, welding, and non-destructive testing, the manufacturing of threaded copper-nickel alloy press-fit sleeves has been successfully achieved. This simplifies the production process of copper-nickel alloy press-fit sleeves, improves the quality and dimensional accuracy of each end of the sleeves, enhances the production efficiency of press-fit sleeves, improves the reliability and stability of the sleeves, and enables mass production of the sleeves. Attached Figure Description

[0044] The accompanying drawings, which constitute a 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.

[0045] In the picture:

[0046] Figure 1 A schematic diagram of a semi-finished internal threaded press-fit sleeve after welding.

[0047] Figure 2 A schematic diagram of a finished internal threaded press-fit sleeve;

[0048] Figure 3 A schematic diagram of a semi-finished external threaded press-fit sleeve after welding;

[0049] Figure 4 This is a schematic diagram of a finished external threaded press-fit sleeve.

[0050] Explanation of reference numerals in the attached drawings: 1. Press-fit pipe fitting; 2. Threaded pipe fitting; 3. Weld. Detailed Implementation

[0051] The inventive concepts of this disclosure will be described below using terminology commonly used by those skilled in the art to communicate the essence of their work to others skilled in the art. However, these inventive concepts may be embodied in many different forms and should not be construed as limited to the embodiments described herein.

[0052] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0053] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0054] In existing technologies, conventional stainless steel press-fit pipe fittings are all manufactured using argon arc welding. However, during the welding process of threaded stainless steel press-fit pipe fittings using argon arc welding, the long welding time results in a prolonged high-temperature residence time in the weld zone and near-weld zone, which can easily lead to microscopic chemical segregation in the weld zone. This makes stainless steel press-fit pipe fittings unsuitable for use in harsh environments or for conveying corrosive liquids. Furthermore, the quality of argon arc welded joints is easily affected by factors such as welding process, welding equipment, gas protection, and the skill level of the welders, resulting in a high degree of instability in product quality. Consequently, due to the differences in price, hardness, acid resistance, weldability, and thermal conductivity between stainless steel and copper-nickel alloys, the production process and quality control of steel sleeves cannot meet the requirements for the production of copper-nickel alloy sleeves. Moreover, there are no publicly reported methods for manufacturing threaded copper-nickel alloy press-fit sleeves.

[0055] To address the problem that the existing manufacturing process for steel press-fit sleeves cannot meet the requirements of the manufacturing process for copper-nickel alloy press-fit sleeves due to the performance differences between stainless steel and copper-nickel alloys, this embodiment proposes a method for manufacturing threaded copper-nickel alloy press-fit sleeves. The sleeve prepared by this method is composed of a press-fit fitting 1 and a threaded fitting 2 welded together. A weld 3 is formed at the connection between the press-fit fitting 1 and the threaded fitting 2. The end of the press-fit fitting 1 closest to the threaded fitting 2 is called the welded end of the press-fit fitting 1, and the end of the press-fit fitting 1 furthest from the threaded fitting 2 is called the press-fit end of the press-fit fitting 1. The end of the threaded fitting 2 closest to the press-fit fitting 1 is called the welded end of the press-fit fitting 1, and the end of the threaded fitting 2 furthest from the press-fit fitting 1 is called the threaded end of the press-fit fitting 1. The method includes the following steps:

[0056] Step 1: Prepare press-fit pipe fitting 1 using a press-fit pipe fitting forming machine;

[0057] Step 2: Prepare threaded pipe fitting 2 and pre-process it;

[0058] Step 3: Welding: Weld the press-fit fitting 1 to the threaded fitting 2 to form the shape;

[0059] Step 4: Non-destructive testing: Inspect weld 3;

[0060] Step 5: Machining to obtain the finished press-fit sleeve.

[0061] The aforementioned preparation method effectively simplifies the production process of copper-nickel alloy press-fit bushings, improves the quality and dimensional accuracy of each end of the copper-nickel alloy press-fit bushing, enhances the production efficiency of press-fit bushings, improves the reliability and stability of bushings, and enables mass production of bushings.

[0062] Step one includes:

[0063] Step S11: Cutting: Using seamless copper-nickel alloy tubing as raw material, cut the tubing to the first specified size and remove the burrs from both ends of the tubing;

[0064] Step S12: Forming: Apply stretching oil to both the inner and outer sides of both ends of the pipe, and use a conventional press-fit pipe forming machine to prepare the pipe into a press-fit pipe. The press-fit pipe is a pipe fitting that can be press-fitted at both ends, and the stretching oil is a conventional stamping stretching oil that can be purchased on the market.

[0065] Step S13: Wire cutting: The two ends of the crimp tube are cut by wire cutting to form two crimp fittings 1. Both crimp fittings 1 can be matched with threaded fittings 2 for welding sleeves.

[0066] Step S14: Pipe cleaning: Place the two press-fit pipe fittings 1 into an ultrasonic cleaner for degreasing.

[0067] Step S15: Annealing treatment: Anneal the two formed press-fit pipe fittings 1 and then proceed to step two;

[0068] Step S15 includes: annealing the two formed press-fit pipe fittings 1, placing the press-fit ends of the two press-fit pipe fittings 1 into a nitrogen-protected furnace for annealing, and holding the press-fit pipe fittings 1 at the furnace temperature during the annealing process, and removing the press-fit pipe fittings 1 when the furnace cools them to the first preset temperature T1; the heating temperature of the nitrogen-protected furnace during the annealing of the press-fit pipe fittings 1 is 700℃-780℃, and the holding time during the furnace temperature rise is 30min-45min; after the annealing treatment, the hardness of both ends of the press-fit pipe fittings 1 is <120HV5.

[0069] Using the method described in step one, two press-fit pipe fittings 1 can be produced simultaneously by wire cutting in the case of a single production of press-fit pipe fittings. This greatly improves the efficiency of mass production of sleeves, reduces the cost of sleeve production, reduces the amount of loss during the preparation of press-fit pipe fittings 1, and greatly improves the reliability of sleeve production.

[0070] Step two includes:

[0071] Step S21: Material cutting: Using copper-nickel alloy ingots as raw materials, cut the ingots according to the second specification dimensions;

[0072] Step S22: Forging: After heating and holding the copper-nickel alloy ingot in an electric furnace, the ingot is forged into a semi-finished forging of threaded pipe fitting 2 with a target outer diameter of R1.

[0073] Step S23: Non-destructive testing: Perform ultrasonic testing on the semi-finished forging and determine whether it is qualified based on the test results. If yes, proceed to step S24; otherwise, return to step S22. Specifically, step S23 includes: Non-destructive testing: Perform ultrasonic testing on the semi-finished forging and determine whether the test results meet the requirements of GB / T3310-2010 "Ultrasonic Testing of Copper Alloy Bars". If yes, proceed to step S24; otherwise, return to step S22.

[0074] Step S24: Pre-machining: Perform finishing on the semi-finished forgings and then proceed to step three;

[0075] In step S22, the electric furnace heating temperature is 920℃-960℃, the holding time t0 is 30min-60min, the ingot forging adopts free forging method, and the final forging temperature is ≥ the second preset temperature T2. During the forging process, when the ingot billet needs to be reheated in the furnace, the holding time t after reheating is one-third of the first holding time t0, that is, t=t0 / 3±a, where a is the error coefficient of the holding time, and T1 and T2 are preset temperature values, which are set according to the requirements.

[0076] Furthermore, since the threaded pipe fitting 2 and the press-fit pipe fitting 1 need to be connected by butt welding, that is, the welding end of the threaded pipe fitting 2 and the welding end of the press-fit pipe fitting 1 are connected by alignment welding, the semi-finished forging of the threaded pipe fitting 2 needs to be pre-processed. Step S24 includes:

[0077] Step S241: Perform precision machining on the welding end of the semi-finished forging of threaded pipe fitting 2. The machining length of the welding end of the semi-finished forging of threaded pipe fitting 2 is the same as the machining length of the welding end of the press-fit pipe fitting 1, and the machining length is 4mm-6mm. The threaded end of the semi-finished forging of threaded pipe fitting 2 needs to be machined after the press-fit pipe fitting 1 and the threaded pipe fitting 2 are welded.

[0078] Step S242: Pre-process the outer diameter R1 of the threaded end of the semi-finished forging. The maximum outer diameter of the threaded end of the finished threaded pipe fitting 2 is denoted as R2, R1>R2, and the difference between R1 and R2 is in the range of 2mm-4mm.

[0079] Step S243: Determine whether the inner diameter r1 of the semi-finished forging is less than the first preset inner diameter value r0. If yes, proceed to step S244; otherwise, proceed to step S245.

[0080] Step S244: Select whether to perform internal diameter pre-machining. If yes, proceed to step S245; otherwise, proceed to step three.

[0081] Step S245: Pre-process the inner diameter of the threaded end of the semi-finished forging and execute step three. The minimum outer diameter of the threaded end of the finished threaded pipe fitting 2 is denoted as r2, r1>r2, and the difference between r2 and r1 is in the range of 2mm-4mm.

[0082] In this embodiment, preferably, the first preset inner diameter value r0 is 20mm and the second preset temperature T2 is 750℃, but it can be set according to actual needs.

[0083] By using free forging in step two to prepare the threaded pipe fitting 2, the quality of the threaded pipe fitting 2 can be improved, making the internal structure of the threaded pipe fitting 2 more uniform. The multiple forging process can make the performance of the threaded pipe fitting 2 better, greatly improving the quality of the casing and enhancing the reliability and corrosion resistance of the casing.

[0084] Step three includes:

[0085] Step S31: Preparation before welding: Remove surface impurities from the welding end of the press-fit pipe fitting 1 and the welding end of the threaded pipe fitting 2 respectively. The surface impurities can be removed by mechanical methods and / or organic solvent cleaning. In this embodiment, "welding end" refers to the location of the welding surface, and the location of the end of the press-fit pipe fitting 1 near the welding surface and the end of the threaded pipe fitting 2 near the welding surface.

[0086] Step S32: Assemble the press-fit pipe fitting 1 and threaded pipe fitting 2: Use laser-arc hybrid welding method to efficiently weld the press-fit pipe fitting 1 and threaded pipe fitting 2. Connect the press-fit pipe fitting 1 and threaded pipe fitting 2 to the welding operation table through the matching tools of laser-arc hybrid welding, and teach the laser.

[0087] Step S33: Welding and fixing: After the assembly of the press-fit pipe fitting 1 and the threaded pipe fitting 2 is completed, the welding ends of the press-fit pipe fitting 1 and the threaded pipe fitting 2 are positioned and welded to form a weld 3, and the inner side of the weld 3 is filled with protective gas. In this embodiment, the "inner side of the weld 3" refers to the side of the weld 3 facing the inside of the semi-finished sleeve.

[0088] Step S34: Weld strictly in accordance with the requirements of the welding process specification to obtain a semi-finished press-fit sleeve. During welding, it is necessary to set the average power of the laser, welding speed, working distance, laser pulse wave form, peak power, base value, frequency, and duty cycle. It is also necessary to set the composite automatic current value and arc voltage value.

[0089] Step S35: After welding is completed, check the surface quality of weld 3 of the semi-finished press-fit sleeve.

[0090] The laser-arc hybrid welding method used in step three achieves high-efficiency welding. Compared with the most widely used manual argon arc welding, the laser-arc hybrid welding method has several advantages. First, it eliminates the need for filler wire at weld seam 3, and the beveling of the press-fit fitting 1 and threaded fitting 2 does not require additional processing. Second, this method has low heat input, negligible deformation, fast welding speed, high pinhole stability, and better weld seam 3 formation, which greatly improves the welding quality. It also prevents the sleeve welding area from being damaged under harsh conditions or high corrosion, thus greatly improving the quality and service life of the sleeve.

[0091] Step four includes:

[0092] Step S41: Non-destructive testing: Perform radiographic testing on weld 3 and determine whether the radiographic testing results meet the requirements of NB / T47013.2 Class II. If yes, proceed to step S42; otherwise, return to step three.

[0093] Step S42: Perform penetrant testing on weld 3 and determine whether the penetrant testing results meet the requirements of NB / T47013.5 Class I. If yes, proceed to step five; otherwise, return to step three.

[0094] In step five, the semi-finished press-fit sleeve that has passed non-destructive testing is precision machined according to the drawings to obtain the finished press-fit sleeve. The precision machining includes machining threads on the semi-finished press-fit sleeve. The threads include internal threads and external threads. The specific machining of the threads is based on the requirements of the drawings and is machined into internal threads or external threads.

[0095] Preferably, the order of X-ray detection and penetrant testing in step four can be interchanged, but both must meet the corresponding testing standards to determine whether they are qualified.

[0096] By performing non-destructive testing on the semi-finished press-fit sleeve in steps four and five before machining, it is possible to determine whether the internal structure of the semi-finished sleeve meets the requirements through various forms of testing. This avoids the possibility of rework due to the sleeve's internal structure not meeting standards after premature thread machining. By adopting the method of testing first and then machining according to drawings, the preparation time of press-fit sleeves is effectively shortened, the process flow of sleeve preparation is simplified, the process complexity of sleeve preparation is reduced, the quality of sleeves is guaranteed, the service life of sleeves is improved, the amount of loss during the sleeve production process is reduced, and the mass production of sleeves is effectively realized.

[0097] Example 1:

[0098] This invention has been applied to the manufacture of copper-nickel alloy OD54xRp2" internal thread press-fit sleeves, and the specific steps are as follows:

[0099] Step 1: Preparation method of press-fit pipe fitting 1:

[0100] Step S11: Cutting: Using copper-nickel alloy seamless pipe Φ54x1.5mm as raw material, cut the pipe to the first specification size, i.e., 102±1mm, and remove the end burrs;

[0101] Step S12: Forming: Apply stretching oil evenly to the inner and outer surfaces of both ends of the pipe, and use a conventional press-fit pipe forming machine to prepare the pipe into a press-fit pipe. The press-fit pipe is a pipe fitting that can be pressed at both ends, and the length of the press-fit pipe is 87±2mm.

[0102] Step S13: Wire cutting: The pipe fitting produced in step S12 is evenly divided into two press-fit pipe fittings 1 by wire cutting. Both press-fit pipe fittings 1 can be used to weld sleeves.

[0103] Step S14: Pipe cleaning: Place the press-fit pipe 1 produced in step S13 into an ultrasonic cleaner for degreasing.

[0104] Step S15: Annealing treatment: The formed press-fit pipe fitting 1 needs to be annealed; the press-fit end elbow of the press-fit pipe fitting 1 is placed in a nitrogen-protected furnace for annealing. The press-fit pipe fitting 1 is heated with the furnace. The heating temperature of the nitrogen-protected furnace is 750±10℃. The holding time of the heated pipe fitting 1 is 40min. After cooling to 100℃ in the furnace, it is taken out; the end hardness of the press-fit pipe fitting 1 after annealing is 80-110HV5.

[0105] Step 2, Preparation method of threaded pipe fitting 2:

[0106] The length of the finished threaded pipe fitting 2 is 40±2mm, the maximum outer diameter of the finished threaded pipe fitting 2 is 69mm, the minimum inner diameter of the finished threaded pipe fitting 2 is 41mm, and the welding end size of the finished threaded pipe fitting 2 for butt welding is Φ54x1.5mm.

[0107] Step S21: Cutting: Forge a Φ77x1000mm bar according to the second specification size and weight required. Use a Φ145mm copper-nickel alloy ingot as raw material and cut it to a length of 280mm, with a weight of 42kg.

[0108] Step S22: Forging: Heat the copper-nickel alloy ingot to 950±10℃ in an electric furnace, hold for 50 minutes, and forge the ingot to the target shape using free forging. The final forging temperature is ≥750℃. When the billet needs to be reheated in the furnace, the holding time is 15 minutes. The threaded pipe fittings 2 semi-finished forging joints manufactured by the forging method adopted have a more uniform structure and better performance.

[0109] Step S23: Non-destructive testing: Perform ultrasonic testing on the semi-finished forgings. If the results meet the requirements of GB / T3310-2010 "Ultrasonic Testing of Copper Alloy Bars", proceed to step S24.

[0110] Step S24: Pre-machining: Cut a 45±1mm long bar from the semi-finished forging. Since the threaded pipe fitting 2 and the press-fit pipe fitting 1 need to be connected by butt welding, the welding end of the semi-finished forging of the threaded pipe fitting 2 needs to be precision machined to a length of Φ54x1.5mm. The total machining length of the welding end of the semi-finished forging is 4-6mm. The threaded end of the threaded pipe fitting 2 needs to be machined after welding. Therefore, the outer diameter of the remaining part of the semi-finished forging, excluding the machined welding end, is machined to... The inner diameter of the semi-finished forging is machined to

[0111] Step 3, Welding:

[0112] The laser-arc hybrid welding method is used to efficiently weld the welding ends of the press-fit pipe fitting 1 and the threaded pipe fitting 2.

[0113] Step S31: Pre-welding preparation: At the welding position of the press-fit pipe fitting 1 and the threaded pipe fitting 2 and within a longitudinal range of 15mm around it, use mechanical methods to remove the surface oxide scale, and / or use a silk cloth dipped in an appropriate amount of acetone to wipe the welding end clean. After wiping, the surface of the pipe fitting should be free of oil stains and water stains.

[0114] Step S32: Fix the press-fit pipe fitting 1 and threaded pipe fitting 2 and the matching tooling. Check whether there is any shaking during the rotation of the press-fit pipe fitting 1 and threaded pipe fitting 2. After the inspection is qualified, start the equipment and turn on the indicator light for teaching.

[0115] In the T1 mode, the laser is taught to divide the weld 3 into several segments, each about 50mm long. The positions of the areas with obvious deformation are marked, and the number of teaching points is increased at the marked positions. After the teaching is completed, the no-load operation program is performed in the mode of turning on the indicator light, and it is observed whether the motion trajectory deviates from the weld 3. If yes, the offset position is marked and the process returns to step S32; otherwise, step S33 is executed.

[0116] Step S33 includes:

[0117] Step S331: To prevent the parts from moving during welding, after the crimp fitting 1 and threaded fitting 2 are assembled, they can be fixed by positioning welding.

[0118] Step S332: The welded joint between the press-fit pipe fitting 1 and the threaded pipe fitting 2 is not beveled, and the assembly gap is 0-0.5mm; the tack weld length is 4-6mm, and the tack weld spacing is 50mm;

[0119] Step S333: Fill the inside of the press-fit fitting 1 and the threaded fitting 2 with protective gas, the protective gas being 99.99% Ar. Seal the port of the press-fit end of the press-fit fitting 1 and the port of the threaded end of the threaded fitting 2 with paper tape.

[0120] Step S34: Weld according to the process requirements specified in the welding procedure to obtain a semi-finished press-fit sleeve. The laser is set to an average power of 4kW, a welding speed of 900mm / min, a working distance of 310mm, a square wave laser pulse with a peak power of 8kW, a base value of 0, a frequency of 100Hz, and a duty cycle of 50-60. The composite automatic current is set to 80A and the arc voltage to 10V.

[0121] Step S35: After welding is completed, inspect the appearance of weld 3: Weld 3 and base material should have a smooth transition. Weld 3 and the heat-affected zone of weld 3 should be free from any one or more defects such as cracks, lack of fusion, porosity, arc craters, inclusions, and spatter. There should be no arcing points outside weld 3. The base material refers to the press-fit pipe fitting 1 and the threaded pipe fitting 2.

[0122] Step 4: Non-destructive testing

[0123] Weld 3 shall be subjected to radiographic testing and penetrant testing, and the results shall comply with the requirements of NB / T 47013.2 "Non-destructive testing of pressure equipment - Part 2: Radiographic testing" Level II and NB / T 47013.5 "Non-destructive testing of pressure equipment - Part 5: Penetrant testing" Level I, respectively.

[0124] Step 5: Machining: The welded semi-finished press-fit sleeve is precision machined according to the drawings to obtain the final finished press-fit sleeve.

[0125] Example 2:

[0126] This invention has been applied to the manufacture of copper-nickel alloy OD22xR3 / 4" external thread press-fit sleeves, as detailed below:

[0127] Step 1: Preparation method of press-fit pipe fitting 1:

[0128] Step S11: Material cutting: Using copper-nickel alloy seamless pipe Φ24x1.5mm as raw material, cut the pipe to the first specification size, i.e., 70±1mm, and remove the end burrs;

[0129] Step S12: Forming: Apply stretching oil evenly to the inner and outer surfaces of both ends of the pipe, and use a conventional press-fit pipe forming machine to prepare the pipe into a press-fit pipe. The press-fit pipe is a pipe fitting that can be press-fitted at both ends. The press-fit pipe can accommodate Φ22mm pipes, and the total length of the press-fit pipe fitting is 53±2mm.

[0130] Step S13: Wire cutting: The pipe fitting produced in step S12 is divided into two press-fit pipe fittings 1 by wire cutting. Both press-fit pipe fittings 1 can be used to weld sleeves.

[0131] Step S14: Pipe cleaning: Place the press-fit pipe 1 produced in step S13 into an ultrasonic cleaner for degreasing.

[0132] Step S15: Annealing Treatment: The formed press-fit fittings require annealing treatment. The press-fit end elbow of press-fit fitting 1 is placed in a nitrogen-protected furnace for annealing. The furnace temperature is raised to 730±10℃, and the holding time is 35 minutes. After cooling to 100℃ in the furnace, it is removed. The end hardness of the annealed press-fit fitting 1 is 80-110HV5.

[0133] Step 2, Preparation method of threaded pipe fitting 2:

[0134] The length of the finished threaded pipe fitting 2 is 27±2mm, the maximum outer diameter of the finished threaded pipe fitting 2 is 32mm, the minimum inner diameter of the finished threaded pipe fitting 2 is 17mm, and the welding end size of the finished threaded pipe fitting 2 for butt welding is Φ24x1.5mm.

[0135] Step S21: Cutting: According to the required Φ40x1000mm bar size and weight, use Φ100mm copper-nickel alloy ingot as raw material, cut 160mm long, weighing 11kg;

[0136] Step S22: Forging: Heat the copper-nickel alloy ingot to 950±10℃ using an electric furnace and hold for 40 minutes. Forge the ingot to the desired shape using free forging. The final forging temperature is ≥750℃, and the holding time is 13 minutes when the billet needs to be reheated in the furnace. The semi-finished forging joints of threaded pipe fittings manufactured by forging have a more uniform microstructure and better performance.

[0137] Step S23: Non-destructive testing: Perform ultrasonic testing on the semi-finished forgings. If the results meet the requirements of GB / T3310-2010 "Ultrasonic Testing of Copper Alloy Bars", proceed to step S24.

[0138] Step S24: Pre-machining: Cut a 32±1mm long bar from the semi-finished forging. Since the threaded pipe fitting 2 and the press-fit pipe fitting 1 need to be connected by butt welding, the welding end of the semi-finished forging of the threaded pipe fitting 2 needs to be precision machined to a length of Φ24x1.5mm. The total machining length of the welding end of the semi-finished forging is 4-6mm. The threaded end of the threaded pipe fitting 2 needs to be machined after welding. Therefore, the outer diameter of the remaining part of the semi-finished forging, excluding the machined welding end, is machined to... The inner diameter of the semi-finished forging does not require machining.

[0139] Step 3, Welding:

[0140] The laser-arc hybrid welding method is used to efficiently weld the welding ends of the press-fit pipe fitting 1 and the threaded pipe fitting 2.

[0141] Step S31: Pre-welding preparation: Clean the welding position of the press-fit pipe fitting 1 and the threaded pipe fitting 2 and the surrounding 15mm area using mechanical methods to remove the surface oxide scale, and / or use a silk cloth dipped in an appropriate amount of acetone to wipe it clean. The surface should be free of oil stains and water stains.

[0142] Step S32: Fix the press-fit pipe fitting 1 and threaded pipe fitting 2 and the matching tooling. Check whether there is any shaking during the rotation of the press-fit pipe fitting 1 and threaded pipe fitting 2. After the inspection is qualified, start the equipment and turn on the indicator light for teaching.

[0143] In the T1 mode, the laser is taught to divide the weld 3 into several segments, each about 50mm long. The positions of the areas with obvious deformation are marked and the number of teaching points is increased. After the teaching is completed, the no-load operation program is performed in the mode of turning on the indicator light, and it is observed whether the motion trajectory deviates from the weld 3. If yes, the offset position is marked and the process returns to step S32. If no, step S33 is executed.

[0144] Step S33 includes:

[0145] Step S331: To prevent the parts from moving during welding, after the crimp fitting 1 and threaded fitting 2 are assembled, they can be fixed by spot welding.

[0146] Step S332: The welded joint between the press-fit pipe fitting 1 and the threaded pipe fitting 2 is not beveled, and the assembly gap is 0-0.5mm; the tack weld length is 4-6mm, and the tack weld spacing is 50mm;

[0147] Step S333: Fill the inside of the press-fit fitting 1 and the threaded fitting 2 with protective gas, the protective gas being 99.99% Ar, and seal the pipe openings with paper tape;

[0148] Step S34: Weld according to the process requirements specified in the welding procedure to obtain a semi-finished press-fit sleeve. The laser is set to an average power of 3kW, a welding speed of 600mm / min, a working distance of 310mm, a square wave laser pulse with a peak power of 6kW, a base value of 0, a frequency of 100Hz, and a duty cycle of 50-60. The composite automatic current is set to 60A and the arc voltage to 10V.

[0149] Step S35: After welding is completed, inspect the appearance of weld 3: Weld 3 and base material should have a smooth transition. Weld 3 and the heat-affected zone of weld 3 should be free from any one or more defects such as cracks, lack of fusion, porosity, arc craters, inclusions, and spatter. There should be no arcing points outside weld 3. The base material refers to the press-fit pipe fitting 1 and the threaded pipe fitting 2.

[0150] Step 4: Non-destructive testing

[0151] Weld 3 shall be subjected to radiographic testing and penetrant testing, and the results shall comply with the requirements of NB / T 47013.2 "Non-destructive testing of pressure equipment - Part 2: Radiographic testing" Level II and NB / T 47013.5 "Non-destructive testing of pressure equipment - Part 5: Penetrant testing" Level I, respectively.

[0152] Step 5: Machining: The welded semi-finished press-fit sleeve is precision machined according to the drawings to obtain the final finished press-fit sleeve.

[0153] 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 threaded copper-nickel alloy press-fit sleeve, characterized in that, The sleeve prepared by the method is composed of a press-fit fitting (1) and a threaded fitting (2) welded together, and a weld (3) is formed at the connection between the press-fit fitting (1) and the threaded fitting (2). The method includes the following steps: Step 1: Prepare press-fit pipe fittings using a press-fit pipe fitting forming machine (1); Step 2: Prepare threaded pipe fittings (2) and pre-process them; Step 3, Welding: Weld the press-fit fitting (1) and the threaded fitting (2) together to form the shape; Step 4: Non-destructive testing: Inspect the weld (3); Step 5: Machining to obtain the finished press-fit sleeve; Step one includes: Step S11: Cutting: Using seamless copper-nickel alloy tubing as raw material, cut the tubing to the first specified size and remove the burrs from both ends of the tubing; Step S12: Forming: Apply stretching oil to both the inner and outer sides of both ends of the pipe, and prepare the pipe into a press-fit pipe using a conventional press-fit pipe forming machine; Step S13: Wire cutting: The two ends of the crimp tube are cut by wire cutting to form two crimp fittings (1). Both crimp fittings (1) can be matched with threaded fittings (2) for welding sleeves. Step S14: Pipe cleaning: Place the two press-fit pipe fittings (1) into an ultrasonic cleaner for degreasing treatment; Step S15: Annealing treatment: Anneal the two formed press-fit pipe fittings (1) and perform step two; Step two includes: Step S21: Material cutting: Using copper-nickel alloy ingots as raw materials, cut the ingots according to the second specification dimensions; Step S22: Forging: After heating and holding the copper-nickel alloy ingot in an electric furnace, the ingot is forged into a threaded pipe fitting (2) semi-finished forging with a target outer diameter of R1. Step S23: Non-destructive testing: Perform ultrasonic testing on the semi-finished forgings and determine whether they are qualified based on the test results. If yes, proceed to step S24; otherwise, return to step S22. Step S24: Pre-machining: Perform finishing on the semi-finished forgings and then proceed to step three; Step S24 includes: Step S241: Perform precision machining on the welding end of the semi-finished forging of the threaded pipe fitting (2), wherein the machining length of the welding end of the semi-finished forging is the same as the machining length of the welding end of the press-fit pipe fitting (1); Step S242: Pre-machine the outer diameter of the threaded end of the semi-finished forging; Step S243: Determine whether the inner diameter r1 of the semi-finished forging is less than the first preset inner diameter value r0. If yes, proceed to step S244; otherwise, proceed to step S245. Step S244: Select whether to perform internal diameter machining. If yes, proceed to step S245; otherwise, proceed to step three. Step S245: Pre-machine the inner diameter of the threaded end of the semi-finished forging and then proceed to step three.

2. The method for manufacturing a threaded copper-nickel alloy press-fit sleeve according to claim 1, characterized in that, Step S15 includes: annealing the two formed press-fit pipe fittings (1), placing both press-fit pipe fittings (1) into a nitrogen-protected furnace for annealing, and keeping the press-fit pipe fittings (1) warm by heating with the furnace during the annealing process, and taking out the press-fit pipe fittings (1) when the press-fit pipe fittings (1) are cooled with the furnace to the first preset temperature T1.

3. The method for manufacturing a threaded copper-nickel alloy press-fit sleeve according to claim 2, characterized in that, When the press-fit pipe fitting (1) is annealed, the heating temperature of the nitrogen-protected furnace is 700℃-780℃, and the holding time with the furnace heating is 30min-45min; after the press-fit pipe fitting (1) is annealed, the hardness of both ends of the press-fit pipe fitting (1) is <120HV5.

4. The method for manufacturing a threaded copper-nickel alloy press-fit sleeve according to claim 1, characterized in that, In step S22, the electric furnace heating temperature is 920℃-960℃, the holding time is 30min-60min, the ingot forging adopts free forging method, and the final forging temperature is ≥ the second preset temperature T2.

5. The method for manufacturing a threaded copper-nickel alloy press-fit sleeve according to claim 1, characterized in that, Step three includes: Step S31: Preparation before welding: Remove surface impurities from the welding ends of the press-fit pipe fitting (1) and the threaded pipe fitting (2); Step S32: Assemble the press-fit pipe fitting (1) and threaded pipe fitting (2): Connect the press-fit pipe fitting (1) and threaded pipe fitting (2) to the welding workbench using the matching tools, and perform laser teaching; Step S33: Welding and fixing: After completing the assembly of the press-fit pipe fitting (1) and the threaded pipe fitting (2), the welding ends of the press-fit pipe fitting (1) and the threaded pipe fitting (2) are positioned and welded to form a weld (3), and the inner side of the weld (3) is filled with protective gas. Step S34: Weld according to the welding process flow to obtain a semi-finished press-fit sleeve; Step S35: After welding is completed, check the surface quality of the weld (3) of the semi-finished press-fit sleeve.

6. The method for manufacturing a threaded copper-nickel alloy press-fit sleeve according to claim 1, characterized in that, Step four includes: Step S41: Non-destructive testing: Perform radiographic testing on the weld (3) and determine whether the radiographic testing results meet the requirements of NB / T47013.2 Class II. If yes, proceed to step S42; otherwise, return to step three. Step S42: Perform penetrant testing on the weld (3) and determine whether the penetrant testing results meet the requirements of NB / T 47013.5 Class I. If yes, proceed to step five; otherwise, return to step three.

7. The method for manufacturing a threaded copper-nickel alloy press-fit sleeve according to claim 1, characterized in that, In step five, the semi-finished press-fit sleeve that has passed non-destructive testing is precision machined according to the drawings to obtain the finished press-fit sleeve. The precision machining includes machining threads on the semi-finished press-fit sleeve.

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