A method for manufacturing high-strength high-conductivity thin-walled copper pipe

Abstract

The application relates to a manufacturing method of high-strength high-conductivity ultra-thin-wall copper pipe, which comprises the following steps: copper alloy smelting: the smelting liquid composition comprises the following components in percentage by mass: Ni: 4-4.2%, Ni:Si: 4.0-4.2, and the balance is Cu; extruding out pipe: the copper alloy smelting liquid is cast into a solid ingot, and the solid ingot is extruded out into a pipe blank; water sealing solid solution is carried out on the pipe blank during the extrusion process, and the pipe blank is cooled to the bath temperature; pipe rolling: the pipe blank is rolled into an intermediate pipe blank by adopting a cold rolling process; solid solution treatment: the intermediate pipe blank is heated to above 780 DEG C and is kept for 60-150 min, and then is immersed in water and cooled to the bath temperature; primary stretching: a cold drawing process is adopted to obtain a drawn pipe with smaller pipe diameter and wall thickness; primary aging treatment: the drawn pipe is heated to 350-500 DEG C and is kept for 120-240 min; secondary stretching: a cold drawing process is adopted to obtain a finished product specification pipe with smaller pipe diameter and wall thickness; secondary aging treatment: the pipe blank is heated to 350-450 DEG C and is kept for 120-240 min; straightening, sawing and finishing.

Description

Technical Field

[0001] The invention relates to a method for manufacturing a copper alloy tube, in particular to a method for manufacturing an ultra-thin-wall copper tube. Background Art

[0002] In the technological development of new energy vehicles, fast charging is an important technical research and development direction. The car is connected to the charging pile through a charging gun to achieve fast charging. The key component of the charging gun is the thin-walled copper tube. The fast charging charging gun requires the copper tube to have high strength, good conductivity and extremely thin wall. The extremely thin wall means that the ratio of the copper tube diameter to the wall thickness must be greater than 40.

[0003] There is no standard process for the manufacture of ultra-thin-wall copper alloy tubes. Manufacturers mainly rely on their own production experience to carry out personalized customization based on existing production capacity. As a result, the actual production efficiency and production quality of copper alloy tubes are difficult to unify, which seriously restricts the large-scale development of the industry.

[0004] Patent publication number CN112760520A discloses a chromium-zirconium-copper thin-walled tube and its preparation method. The tube comprises the following main materials in the following mass percentage ratios: 0.4-0.8% metallic chromium, 0.3-0.6% metallic zirconium, 0.2-0.5% cerium, and the balance being electrolytic copper. The thin-walled tube preparation method includes the following steps:

[0005] Step 1) The above components are mixed and added into the degreasing liquid for degreasing and cleaning;

[0006] Step 2), smelting and casting into solid round ingots;

[0007] Step 3) The solid round ingot after casting is sawn to a length of about 400 mm, heated to 1000°C and then subjected to piercing hot extrusion processing. After the product billet is extruded, it is directly put into a water tank to complete the solid solution treatment to make the element content of the product fully uniform;

[0008] Step 4) After the extruded product billet is headed, it is cold drawn. During the process, an intermediate annealing process is required to restore the plasticity of the product to ensure the completion of the process. After 8 cold drawing processes and 50% to 60% cold deformation, it is finally drawn to the finished product. The finished product needs to be aged at a temperature of 460 to 480°C and a holding time of 300 minutes. Summary of the Invention

[0009] The purpose of the present invention is to provide a method for manufacturing a copper-nickel-silicon alloy tube, which is suitable for manufacturing an ultra-thin-wall copper alloy tube for a charging gun, thereby realizing the manufacture of an ultra-thin-wall copper tube with high strength and high conductivity.

[0010] The technical solution adopted by the present invention is: a method for manufacturing a high-strength and high-conductivity ultra-thin-wall copper tube, comprising the following steps:

[0011] Step 1: Copper alloy smelting: alloy composition by mass percentage: Ni: 4-4.2%, Ni:Si 4.0-4.2, balance Cu;

[0012] Step 2: Extrusion of tube: The copper alloy melt is cast into a solid ingot, and the solid ingot is extruded into a tube. The product temperature is 790℃~850℃. During the extrusion process, the tube blank is immersed in water for water sealing and solutionization, and then cooled to the bath temperature.

[0013] Step 3: Rolling the tube: Using the cold rolling process, the tube billet is rolled into an intermediate tube billet, which is subjected to a cold rolling deformation of 68% to 85% to obtain an intermediate tube billet with a smaller diameter and wall thickness;

[0014] Step 4: Solution treatment: Heat the intermediate tube to above 780°C, keep it warm for 60-150 minutes, and cool it to the bath temperature in water;

[0015] Step 5: Primary stretching: Using cold drawing process, the comprehensive cold deformation of the tube diameter and wall thickness is 85% to 95%, obtaining a drawn tube with smaller diameter and wall thickness;

[0016] Step 6: Primary aging treatment: heat the drawn tube to 350°C to 500°C and keep it at this temperature for 120min to 240min;

[0017] Step 7: Secondary stretching: Using cold drawing process, the comprehensive cold deformation of the tube diameter and wall thickness is 35-45%, and the finished tube with smaller diameter and wall thickness is obtained;

[0018] Step 8: Secondary aging treatment: heat the tube to 350℃~450℃ and keep it at this temperature for 120min~240min;

[0019] Step 9: Straightening, sawing and finishing.

[0020] Optionally, in step 2, the diameter of the solid ingot is 180 mm to 300 mm, the diameter of the tube blank is 65 mm to 100 mm, and the wall thickness is 6 mm to 12 mm.

[0021] Optionally, in step three, the specification of the intermediate tube blank is 40 mm to 58 mm, and the wall thickness is 2.2 mm to 3.5 mm.

[0022] Optionally, in step 4, the heating temperature for the solution treatment is 800°C.

[0023] Optionally, in step five, the diameter of the drawn tube is 22 mm to 38 mm, and the wall thickness is 0.40 mm to 0.75 mm.

[0024] Optionally, in step seven, the tube diameter of the final product is 16.50 mm to 28.00 mm, and the wall thickness is 0.30 mm to 0.50 mm.

[0025] The ultra-thin-wall copper tube obtained by the above method has a diameter-to-wall thickness ratio significantly meeting the requirement of being greater than 40, a hardness of 220-270 HV, a tensile strength of 750 MPa-840 MPa, and a conductivity of ≥43% IACS. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a physical picture of the thin-walled copper tube of the present invention. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below with reference to the examples. The examples are illustrative and intended to explain the present invention, but are not to be construed as limiting the present invention.

[0028] Example 1

[0029] This embodiment relates to a method for manufacturing an ultra-thin-wall copper tube with a diameter of 16.80 mm and a wall thickness of 0.30 mm, and the steps are as follows:

[0030] Step 1: Copper alloy smelting: alloy composition by mass percentage: Cu: 95%, Ni: 4%, Si: 1%;

[0031] Step 2: Extrusion of tube: The copper alloy melt is cast into a solid ingot with a diameter of 185 mm. The solid ingot is extruded into a tube at a production temperature of 830°C to obtain a tube blank with a diameter of 65 mm and a wall thickness of 6 mm. During the extrusion process, the tube blank is immersed in water for water sealing and solutionization, and then cooled to bath temperature.

[0032] Step 3: Rolling the tube: Using a cold rolling process, the tube blank is rolled into an intermediate tube blank to obtain an intermediate tube blank with a diameter of 44 mm and a wall thickness of 2.2 mm;

[0033] Step 4: Solution treatment: Heat the intermediate tube to 800°C, keep it warm for 120 minutes, and cool it to the bath temperature by immersing it in water;

[0034] Step 5: Primary drawing: Using a cold drawing process, a drawn tube with a diameter of 22 mm and a wall thickness of 0.40 mm is obtained;

[0035] Step 6: Primary aging treatment: heat the drawn tube to 400°C and keep it at this temperature for 120 minutes;

[0036] Step 7: Secondary drawing: Using cold drawing process, a finished specification tube with a tube diameter of 16.8 mm and a wall thickness of 0.30 mm is obtained;

[0037] Step 8: Secondary aging treatment: heat the tube to 380°C and keep warm for 120 minutes;

[0038] Step 9: Straightening, sawing and finishing.

[0039] The copper tube has a diameter to wall thickness ratio of 56, hardness of 230HV, tensile strength of 790MPa, and electrical conductivity of 52%IACS.

[0040] Example 2:

[0041] This embodiment relates to a method for manufacturing an ultra-thin-wall copper tube with a diameter of 26.70 mm and a wall thickness of 0.45 mm, and the steps are as follows:

[0042] Step 1: Copper alloy smelting: alloy composition by mass percentage: Cu: 95%, Ni: 4.03%, Si: 0.97%;

[0043] Step 2: Extrusion of tube: The copper alloy melt is cast into a solid ingot with a diameter of 260 mm. The solid ingot is extruded into a tube at a production temperature of 850°C to obtain a tube blank with a diameter of 98 mm and a wall thickness of 9 mm. During the extrusion process, the tube blank is immersed in water for water sealing and solutionization, and then cooled to bath temperature.

[0044] Step 3: Rolling the tube: Using a cold rolling process, the tube blank is rolled into an intermediate tube blank to obtain an intermediate tube blank with a diameter of 58 mm and a wall thickness of 2.6 mm;

[0045] Step 4: Solution treatment: Heat the intermediate tube to 800°C, keep it warm for 150 minutes, and cool it to the bath temperature by immersing it in water.

[0046] Step 5: Primary drawing: Using a cold drawing process, a drawn tube with a diameter of 35 mm and a wall thickness of 0.60 mm is obtained;

[0047] Step 6: Primary aging treatment: heat the drawn tube to 400°C and keep it at this temperature for 120 minutes;

[0048] Step 7: Secondary drawing: Using cold drawing process, a finished tube with a diameter of 26.7 mm and a wall thickness of 0.45 mm is obtained;

[0049] Step 8: Secondary aging treatment: heat the tube to 350°C and keep warm for 120 minutes;

[0050] Step 9: Straightening, sawing and finishing.

[0051] The copper tube has a diameter to wall thickness ratio of 59, hardness of 265HV, tensile strength of 810MPa, and electrical conductivity of 53%IACS.

[0052] In addition to the above embodiments, the present invention also includes other implementation methods. Any technical solutions formed by equivalent transformation or equivalent replacement should fall within the scope of protection of the claims of the present invention.

Claims

1. A method for manufacturing a high-strength, high-conductivity, ultra-thin-wall copper tube, comprising the following steps: Step 1: Copper alloy smelting: alloy composition by mass percentage: Ni: 4-4.2%, Ni:Si 4.0-4.2, balance Cu; Step 2: Extrusion of tube: The copper alloy melt is cast into a solid ingot, and the solid ingot is extruded into a tube. The product temperature is 790℃~850℃. During the extrusion process, the tube blank is immersed in water for water sealing and solution, and then cooled to the bath temperature. The diameter of the solid ingot is 180mm-300mm, the diameter of the tube blank is 65mm~100mm, and the wall thickness is 6mm~12mm; Step 3: Rolling the tube: The tube blank is rolled into an intermediate tube blank by cold rolling process. After 68% to 85% cold rolling deformation, the intermediate tube blank with smaller diameter and wall thickness is obtained. The specifications of the intermediate tube blank are 40mm to 58mm and the wall thickness is 2.2mm to 3.5mm. Step 4: Solution treatment: Heat the intermediate tube to above 780°C, keep it warm for 60-150 minutes, and cool it to the bath temperature in water; Step 5: Primary stretching: Using cold drawing process, the comprehensive cold deformation of tube diameter and wall thickness is 85%~95%, and the drawn tube with smaller diameter and wall thickness is obtained. The diameter of the drawn tube is 22mm~38mm and the wall thickness is 0.40mm~0.75mm; Step 6: Primary aging treatment: heat the drawn tube to 350°C~500°C and keep it at this temperature for 120min~240min; Step 7: Secondary stretching: Using cold drawing process, the comprehensive cold deformation of the tube diameter and wall thickness is 35-45%, and the finished tube with smaller diameter and wall thickness is obtained. The final product has a tube diameter of 16.50mm-28.00mm and a wall thickness of 0.30mm-0.50mm. Step 8: Secondary aging treatment: heat the tube to 350℃~450℃ and keep it warm for 120min~240min; Step 9: Straightening, sawing and finishing.

2. The method according to claim 1, wherein: In step 4, the heating temperature for solution treatment is 800°C.

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