High-strength copper-magnesium alloy contact wire for high-speed railway and preparation process of high-strength copper-magnesium alloy contact wire

Abstract

The invention relates to the technical field of contact lines, in particular to a high-strength copper-magnesium alloy contact line for a high-speed railway and a preparation process of the high-strength copper-magnesium alloy contact line. The copper-magnesium alloy contact wire comprises Mg, Cu and P. Cathode copper and a magnesium ingot are adopted as raw materials, and the copper-magnesium alloy contact wire comprises the following chemical components in percentage by mass: 0.40-0.70% of Mg, less than or equal to 0.01% of P, other elements except Mg, P and Cu are classified as impurities, the total amount of the other elements is less than or equal to 0.10%, and the balance of Cu; the preparation process comprises the steps of material preparation, smelting, up-drawing continuous casting, preheating, continuous extrusion and multi-pass drawing, cathode copper is hung at a furnace opening of a crucible furnace to be baked before smelting, then the baked cathode copper is put into the crucible furnace in batches to be smelted, magnesium ingots are put into the crucible furnace after the cathode copper is smelted, stirring is conducted, and the crucible furnace is filled with compressed gas. The technical problems that in the prior art, a copper-magnesium alloy contact wire is high in production cost and cannot meet the tension requirement are effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of catenary, and in particular to a high-strength copper-magnesium alloy catenary for high-speed railways and a preparation process thereof. Background Art

[0002] The catenary mainly refers to the catenary used for the overhead contact system of electrified railways. Its structural characteristics are that it is made of copper, copper-silver alloy, high-strength copper-silver alloy, copper-tin alloy, copper-magnesium alloy, high-strength copper-magnesium alloy, etc. to meet the needs of the overhead contact system of electrified railways. With the rapid development of high-speed railways in China, electrified railways are developing towards high-speed and heavy-haul directions, and higher requirements are put forward for the material and various performances of the catenary with a speed of 350 km / h. However, the existing catenaries are difficult to meet the requirements in terms of mechanical properties.

[0003] In view of the above problems, the patent document with the authorization announcement number CN103276237B discloses a preparation method of a copper-magnesium alloy catenary wire for railway electrification. The composition of the wire includes a copper base and alloy metals. Among them, the weight percentages of the components of the alloy metals are as follows: magnesium 0.5 - 0.6%, zirconium 0.012 - 0.014%, niobium 0.012 - 0.014%, titanium 0.005 - 0.008%, mixed rare earth 0.02 - 0.04%. The mixed rare earth is composed of yttrium, berkelium, and lanthanum, and the mass ratio of the three is 1:0.2:0.5. The preparation method includes four steps: manufacturing a copper-magnesium alloy casting rod by the up-drawing continuous casting method, manufacturing an extrusion rod by the continuous extrusion method, manufacturing a rolling rod by continuous cold rolling, and manufacturing a catenary wire by continuous forming. Among them, the copper-magnesium alloy casting rod manufactured by the up-drawing continuous casting method needs to be preheated to 350°C in an induction heating furnace protected by argon before entering the continuous extruder to be extruded into an extrusion rod.

[0004] Although the tensile strength, elongation, grain size, and toughness of the copper-magnesium alloy catenary wire manufactured by the above preparation method have been greatly improved compared with the existing wires, the content of the copper-magnesium alloy contained therein does not meet the requirements of "TB / T2809 - 2017", and the copper-magnesium alloy casting rod needs to be heated under the protection of argon, which requires high equipment requirements and high production costs.

[0005] In addition, the "Interim Technical Conditions for Overhead Contact System Equipment of 300 - 350 km / h Electrified Railways" (OCS - 3) requires that the rated working tension of the copper alloy catenary wire with a length of 150 mm on the main line ≥ 30 KN, and according to the design requirements, the rated tension working tension of the high-speed rail line with a speed of 400 - 450 km / h ≥ 36 KN. The applicable tension of the catenary is determined by its breaking force, cross-sectional area, and safety factor. Therefore, the greater the tension, the higher the required tensile strength of the catenary. At the same time, the strength of the catenary is also a guarantee of its wear resistance. The catenaries produced by conventional processes cannot meet the above requirements. 2 The rated working tension of the copper alloy catenary wire with a length of 150 mm on the main line ≥ 30 KN, and according to the design requirements, the rated tension working tension of the high-speed rail line with a speed of 400 - 450 km / h ≥ 36 KN. The applicable tension of the catenary is determined by its breaking force, cross-sectional area, and safety factor. Therefore, the greater the tension, the higher the required tensile strength of the catenary. At the same time, the strength of the catenary is also a guarantee of its wear resistance. The catenaries produced by conventional processes cannot meet the above requirements. Summary of the Invention

[0006] The present invention provides a high-strength copper-magnesium alloy contact wire for high-speed railways and its preparation process, so as to solve the technical problems of high production cost of copper-magnesium alloy contact wires in the prior art and inability to meet the tension requirements.

[0007] To solve the above problems, the high-strength copper-magnesium alloy contact wire for high-speed railways provided by the present invention adopts the following technical solutions:

[0008] A preparation process for a high-strength copper-magnesium alloy contact wire for high-speed railways includes the following steps:

[0009] S1: Prepare materials: According to the chemical composition ratio of the copper-magnesium alloy contact wire, calculate the usage amounts of cathode copper and magnesium ingots and prepare materials according to the calculation results.

[0010] S2: Melting and upward continuous casting: Hang the cathode copper at a distance d from the furnace mouth of the crucible furnace for baking to remove the moisture on the cathode copper. The baking time is t. Batch the baked cathode copper and put it into the crucible furnace for melting. After the cathode copper melts, put in the magnesium ingots and stir, and add a covering agent on the surface of the copper liquid. Compressed gas is filled in the crucible furnace. Then, cool it through the crystallizer and draw it through the traction device to obtain a copper-magnesium alloy casting rod; the temperature of the copper liquid during melting is 1170 - 1210 °C, the upward drawing temperature is 1170 - 1210 °C, the traction speed is 200 - 500 mm / min, the depth of the crystallizer inserted into the melt is 160 - 310 mm, the water inlet temperature of the crystallizer is 25 - 50 °C, the pressure range of the compressed gas is 0.4 - 0.8 MPa, the covering agent is baked for at least 2.5 h before entering the furnace, the covering thickness of the covering agent on the copper liquid is not less than 100 mm, the covering agent is cleaned every 8 h, and the oxygen content of the copper-magnesium alloy casting rod is controlled below 5 ppm.

[0011] S3: Preheat: Take a 1800 - 2400 mm copper-magnesium alloy casting rod and break it evenly into 6 - 8 pieces, and preheat it using a precision high-temperature forced-air oven to make its temperature reach 680 ± 10 °C.

[0012] S4: Continuous extrusion: First, preheat the surface of the extrusion wheel in the continuous extruder, and then introduce the preheated 6 - 8 copper-magnesium alloy casting rods into the continuous extruder for extrusion to obtain an extrusion rod with a diameter of 26 - 28 mm; the extrusion stress σ of the extruder ≥ 1000 MPa, the extrusion temperature is 550 - 580 °C, the extrusion waste rate is 5.5 - 7.5%, the overflow gap is 0.65 - 0.85 mm, the main shaft rotation speed of the extruder is 4 - 4.5 rpm, the working surface of the plug in the extruder is a curved surface, and the radius of curvature is 36 ± 1 mm.

[0013] S5: Multi-pass drawing: Insert the extrusion rod into the drawing equipment and draw it successively through multiple drawing dies arranged at intervals from front to back in the drawing equipment to obtain a copper-magnesium alloy contact wire with a cross-section of 150 mm 2 and the radial dimensions of the die holes of the multiple drawing dies decrease successively from front to back.

[0014] The beneficial effects of the preparation process of the high-strength copper-magnesium alloy contact wire for high-speed railways provided by the present invention are as follows:

[0015] 1. During smelting and upward continuous casting, baking the cathode copper first can remove the moisture on the surface of the cathode copper, thereby reducing the generation of gas during the smelting process. This can not only reduce the risk of hollow copper-magnesium alloy casting rods but also avoid the formation of inclusions due to the combination of moisture with other impurities during the smelting process; optimize the temperature of the molten copper and the upward drawing temperature during smelting from the existing 1170 - 1250 °C to 1170 - 1210 °C, reduce the loss of magnesium during the smelting process, reduce the low fluctuation of the magnesium content in the copper-magnesium alloy casting rods, improve the quality of the copper rods; optimize the drawing speed from the existing 200 - 800 mm / min to 200 - 500 mm / min. While comprehensively stabilizing the output, it reduces defects such as loose structure in the copper-magnesium alloy casting rods caused by the drawing speed, improves the internal quality of the copper-magnesium alloy casting rods, and ultimately improves the quality, tension, and yield rate of the copper-magnesium alloy contact wire;

[0016] 2. Optimize the number of copper-magnesium alloy casting rods introduced into the continuous extruder from the existing 4 to 6 - 8, increase the number of pre-heated copper-magnesium alloy casting rods introduced into the continuous extruder, further stabilize the initial internal temperature of the continuous extruder, avoid uneven thermal expansion and contraction of the copper-magnesium alloy casting rods due to unstable initial temperature during the heating and cooling processes, and at the same time reduce the temperature gradient inside the copper-magnesium alloy casting rods, thereby reducing the risk of thermal stress and cracks. The stable initial temperature can also provide favorable conditions for the dynamic recrystallization of the metal, promote the refinement of grains, improve the mechanical properties such as strength and hardness of the extrusion rod obtained by extrusion, and ultimately achieve the improvement of the internal quality of the extrusion rod;

[0017] 3. During the extrusion process, the working surface of the plug is a curved surface, which can make the copper-magnesium alloy casting rod pass through a fixed radius of curvature and directly enter the die inlet of the extrusion die along a fixed curve, smoothly enter the extrusion die for forming, greatly reduce or eliminate the defects inside the extrusion rod obtained by extrusion. In addition, this orderly flow pattern makes the copper-magnesium alloy casting rod enter the extrusion die more smoothly, reduces the force required to guide and regularize the flow direction of the copper-magnesium alloy casting rod, and thus reduces the energy consumption.

[0018] Through the above settings, the present invention effectively solves the technical problems of high production cost and inability to meet the tension requirements of copper-magnesium alloy contact wires in the prior art.

[0019] Further, in step S2, the diameters of the obtained copper-magnesium alloy casting rods by traction are 20 mm, 25 mm, and 30 mm.

[0020] Further, in step S5, a limiting structure is installed in front of the entrance of each drawing die to limit the degree of freedom of the extrusion rod, and the limiting gap of the limiting structure is 3 - 8 mm.

[0021] Beneficial effects: By arranging a limiting structure in front of the entrance of each drawing die, the degree of freedom of the extrusion rod can be limited, the vibration of the extrusion rod during the drawing process can be reduced, the uniformity of the grain size in the extrusion rod and the stability of the mechanical properties during the drawing process can be improved, and at the same time, the service life of the drawing die can be extended, and the production cost of the copper-magnesium alloy contact wire can be reduced.

[0022] Further, the die entrance angle of the drawing die at the very front end of the drawing equipment is 18°, and the die entrance angles of the drawing dies in the drawing equipment decrease successively from front to back.

[0023] Beneficial effects: During the multi-pass drawing process, as the drawing progresses, the extrusion rod gradually becomes longer and thinner, and its deformation resistance also increases accordingly. Gradually reducing the die entrance angle can make the extrusion rod more easily enter the drawing die, reduce the deformation resistance, thereby reducing the drawing force, increasing the drawing speed, reducing the drawing interruption or reject rate caused by poor deformation, and further improving the drawing efficiency.

[0024] Further, the die entrance angle of each drawing die is 1 - 1.5° smaller than that of the previous drawing die.

[0025] Further, in step S5, the concentration of the cooling grease in the drawing die is 16 - 18%, and an extrusion rod cooling structure is provided on the drawing die, and the concentration of the cooling grease in the extrusion rod cooling structure is 12 - 15%.

[0026] Further, in step S2, the suspension distance d is 10 - 30 cm, and the baking time t is greater than or equal to 10 min.

[0027] Further, in step S2, the covering agent is carbon black or graphite powder or charcoal.

[0028] To solve the above problems, the high-strength copper-magnesium alloy contact wire for high-speed railways provided by the present invention adopts the following technical solutions:

[0029] A high-strength copper-magnesium alloy contact wire for high-speed railways, comprising Mg, Cu, and P, is prepared by the above-mentioned preparation process for high-strength copper-magnesium alloy contact wires for high-speed railways. Using cathode copper and magnesium ingots as raw materials, by mass percentage, the chemical composition of the copper-magnesium alloy contact wire includes: Mg: 0.40 - 0.70%, P: ≤0.01%. Other elements except Mg, P, and Cu are classified as impurities, and their total amount is ≤0.10%, with the balance being Cu.

[0030] The high-strength copper-magnesium alloy contact wire for high-speed railways provided by the present invention is prepared by the above-mentioned preparation process. This process has improved the melting upward continuous casting, continuous extrusion, and multi-pass drawing, and has achieved the following beneficial effects:

[0031] 1. During the melting upward continuous casting, baking the cathode copper first can remove the moisture on the surface of the cathode copper, thereby reducing the generation of gas during the melting process. This can not only reduce the risk of hollow copper-magnesium alloy casting rods but also avoid the formation of inclusions due to the combination of moisture with other impurities during the melting process; the temperature of the copper liquid and the upward drawing temperature during melting are optimized from the existing 1170 - 1250°C to 1170 - 1210°C, reducing the loss of magnesium during the melting process, reducing the low fluctuation of the magnesium content in the copper-magnesium alloy casting rods, improving the quality of the copper rods; the drawing speed is optimized from the existing 200 - 800 mm / min to 200 - 500 mm / min. While comprehensively stabilizing the output, it reduces defects such as loose structure in the copper-magnesium alloy casting rods caused by the drawing speed, improves the internal quality of the copper-magnesium alloy casting rods, and ultimately improves the quality, tension, and yield rate of the copper-magnesium alloy contact wire;

[0032] 2. The number of copper-magnesium alloy casting rods introduced into the continuous extruder is optimized from the existing 4 to 6 - 8, increasing the number of pre-heated copper-magnesium alloy casting rods introduced into the continuous extruder, further stabilizing the initial internal temperature of the continuous extruder, avoiding uneven thermal expansion and contraction caused by unstable initial temperature during the heating and cooling processes of the copper-magnesium alloy casting rods, and at the same time reducing the temperature gradient inside the copper-magnesium alloy casting rods, thereby reducing the risk of thermal stress and cracks. The stable initial temperature can also provide favorable conditions for the dynamic recrystallization of the metal, promote the refinement of grains, improve the mechanical properties such as strength and hardness of the extruded rods, and ultimately achieve the improvement of the internal quality of the extruded rods;

[0033] 3. During the extrusion process, the working surface of the plug is a curved surface, which can make the copper-magnesium alloy casting rod pass through a fixed radius of curvature and directly enter the inlet of the extrusion die along a fixed curve, smoothly entering the extrusion die for forming, greatly reducing or eliminating the defects inside the extruded rods obtained by extrusion. In addition, this orderly flow mode makes the copper-magnesium alloy casting rod enter the extrusion die more smoothly, reducing the force required to guide and regularize the flow direction of the copper-magnesium alloy casting rod, thereby reducing the energy consumption.

[0034] With the above settings, the present invention effectively solves the technical problems in the prior art that the production cost of the copper-magnesium alloy contact wire is high and the tension requirement cannot be met.

[0035] Further, in terms of mass percentage, in the cathode copper, Cu: ≥99.95%, and in the magnesium ingot, Mg: 99.995%. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] By referring to the accompanying drawings and reading the following detailed description, the above and other objects, features, and advantages of the exemplary embodiments of the present invention will become readily understandable. In the drawings, several embodiments of the present invention are shown in an exemplary rather than restrictive manner, and the same or corresponding reference numerals represent the same or corresponding parts, wherein:

[0037] Figure 1 is a flowchart of the preparation process for the high-strength copper-magnesium alloy contact wire provided by the present invention for high-speed railways;

[0038] Figure 2 is an application structural schematic diagram of the melting up-drawing continuous casting device;

[0039] Figure 3 is an application structural schematic diagram of the precision high-temperature forced-air oven;

[0040] Figure 4 is a schematic diagram of the working principle of the continuous extruder Figure 1 ;

[0041] Figure 5 is a schematic diagram of the working principle of the continuous extruder Figure 2 ;

[0042] Figure 6 is an application structural schematic diagram of the drawing device;

[0043] Figure 7 is the front view of the limiting structure;

[0044] Figure 8 is the side view of the limiting structure.

[0045] Description of the reference numerals:

[0046] 1. Cathode copper; 2. Crucible furnace; 3. Copper liquid; 4. Covering agent; 5. Crystallizer; 6. Copper-magnesium alloy casting rod; 7. Precision high-temperature forced-air oven; 8. Extrusion wheel; 9. Compaction wheel; 10. Plug; 11. Extrusion die; 12. Cover plate; 13. Extrusion rod; 14. Main shaft; 15. Limiting structure; 16. Drawing die; 17. Extrusion rod cooling structure; 18. Pay-off device; 19. Take-up device; 20. Limiting groove; 21. Copper-magnesium alloy contact wire; 22. Traction device; 23. Hanging structure. Specific Embodiments

[0047] The following will elaborate on the principles and spirit of the present invention in detail with reference to several representative embodiments of the present invention.

[0048] An embodiment of the preparation process of a high-strength copper-magnesium alloy contact wire for high-speed railways provided by the present invention:

[0049] As Figure 1 shown, the preparation process of the high-strength copper-magnesium alloy contact wire for high-speed railways includes the following steps:

[0050] S1: Prepare materials: According to the chemical composition ratio of the copper-magnesium alloy contact wire, calculate the usage amounts of cathode copper and magnesium ingots and prepare materials according to the calculation results;

[0051] S2: Melting and upward continuous casting: Hang the cathode copper at a distance d from the furnace mouth of the crucible furnace for baking to remove the moisture on the cathode copper. The baking time is t. Put the baked cathode copper into the crucible furnace for melting in batches. After the cathode copper melts, put in the magnesium ingots and stir, and add a covering agent on the surface of the molten copper. Compressed gas is filled in the crucible furnace. Then, cool through the crystallizer and draw through the traction device to obtain a copper-magnesium alloy cast rod; the temperature of the molten copper during melting is 1170 - 1210 °C, the upward drawing temperature is 1170 - 1210 °C, the drawing speed is 200 - 500 mm / min, the depth of the crystallizer inserted into the melt is 160 - 310 mm, the water inlet temperature of the crystallizer is 25 - 50 °C, the pressure range of the compressed gas is 0.4 - 0.8 MPa, the covering agent is baked for at least 2.5 h before entering the furnace, the covering thickness of the covering agent on the molten copper is not less than 100 mm, the covering agent is cleaned every 8 h, and the oxygen content of the copper-magnesium alloy cast rod is controlled below 5 ppm;

[0052] S3: Preheat: Take a 1800 - 2400 mm copper-magnesium alloy cast rod and break it evenly into 6 - 8 pieces, and preheat it with a precision high-temperature air blast oven to make its temperature reach 680 ± 10 °C;

[0053] S4: Continuous extrusion: First, preheat the surface of the extrusion wheel in the continuous extruder, and then introduce the preheated 6 - 8 copper-magnesium alloy cast rods into the continuous extruder for extrusion to obtain an extrusion rod with a diameter of 26 - 28 mm; the extrusion stress σ of the extruder ≥ 1000 MPa, the extrusion temperature is 550 - 580 °C, the extrusion waste rate is 5.5 - 7.5%, the overflow gap is 0.65 - 0.85 mm, the main shaft speed of the extruder is 4 - 4.5 rpm, the working surface of the plug in the extruder is a curved surface, and the radius of curvature is 36 ± 1 mm;

[0054] S5: Multi-pass drawing: Introduce the extrusion rod into the drawing equipment and draw it successively through multiple drawing dies arranged at intervals from front to back in the drawing equipment to obtain a cross-section of 150 mm2 For the copper-magnesium alloy contact wire, the radial dimension of the die hole of the multi-pass drawing die decreases successively from front to back.

[0055] Define the right end of the drawing equipment as the front and the left end as the back.

[0056] In step S2, the diameters of the drawn copper-magnesium alloy casting rods are 20 mm, 25 mm, and 30 mm; the suspension distance d is 10 - 30 cm, the baking time t is greater than or equal to 10 min; the covering agent is carbon black or graphite powder or charcoal.

[0057] In step S5, a limiting structure is installed in front of the entrance of each drawing die to limit the freedom degree of the extrusion rod. The limiting gap of the limiting structure is 3 - 8 mm; the die entrance angle of the drawing die at the very front end of the drawing equipment is 18°, and the die entrance angles of the drawing dies inside the drawing equipment decrease successively from front to back, and the die entrance angle of each drawing die is 1 - 1.5° smaller than that of the previous drawing die; the concentration of the cooling grease inside the drawing die is 16 - 18%, and an extrusion rod cooling structure is provided above the straightening die, and the concentration of the cooling grease inside the extrusion rod cooling structure is 12 - 15%.

[0058] The performances of three copper-magnesium alloy contact wire samples (i.e., sample 1, sample 2, and sample 3) prepared by the above preparation process and a copper-magnesium alloy contact wire prepared by the existing process (i.e., the comparative example) are tested. The testing conditions are: speed grade: 400 - 450 km / h, test tension: 36 - 42 KN, and the electro-mechanical performance test is carried out in accordance with TB / T2809 - 2017. The test results are shown in Table 1.

[0059] Table 1

[0060]

[0061]

[0062] It can be seen that the parameters such as the tensile strength, breaking force, resistivity, and conductivity of the copper-magnesium alloy contact wire prepared by the above preparation process are all superior to those of the copper-magnesium alloy contact wire prepared by the existing process, and its tensile strength reaches above 580 MPa, the conductivity exceeds the standard requirements, and other electro-mechanical performances and physical and chemical performances also meet or exceed the requirements of the iron standard TB / T2809 - 2017 for copper-magnesium alloy contact wires, and it is applicable to 400 km / h high-speed railway lines.

[0063] The above preparation process is implemented by Figures 2 to 8 the device described above. As Figure 2As shown in the figure, the melting upward continuous casting device used in the melting upward continuous casting step includes a support frame. Below the support frame, there is a crucible furnace 2. On the support frame, directly above the crucible furnace 2, there is a hanging structure 23 for hanging cathode copper 1 and a traction device 22 for pulling the copper-magnesium alloy casting rod 6. Below the traction device 22, there is a mold 5 extending into the crucible furnace 2. Above the molten copper 3 in the crucible furnace 2, a covering agent 4 is added.

[0064] As Figure 3 shown, during preheating, the copper-magnesium alloy casting rod 6 is placed in a precision high-temperature forced-air oven 7.

[0065] As Figure 4 and Figure 5 shown, during continuous extrusion, the copper-magnesium alloy casting rod 6 is extruded through an extrusion channel formed between a compaction wheel 9 and an extrusion wheel 8, and then successively passes through a plug 10, an extrusion die 11, and a cover plate 12 to output an extruded rod 13 that is extruded and formed. The extrusion main shaft 14 is connected to the extrusion wheel 8.

[0066] As Figure 6 shown, during multi-pass drawing, the wire pay-off device 18 at the right end of the drawing equipment first releases the extruded rod 13. Then, the extruded rod 13 passes successively through five drawing dies 16 arranged on the left side of the wire pay-off device 18 from right to left for drawing and forming. During the drawing process, the extruded rod 13 is cooled by the coolant inside the drawing die and the extrusion rod cooling structure 17. Finally, the copper-magnesium alloy contact wire 21 obtained by drawing is collected by a wire take-up device 19.

[0067] In addition, during multi-pass drawing, a limiting structure 15 is provided at the entrance of each drawing die 16. As Figure 7 and Figure 8 shown, the limiting structure 15 is located above the extruded rod 13 and is a vertically arranged disc-shaped structure. The limiting structure 15 has a limiting groove 20 arranged circumferentially around it.

[0068] It should be noted that the copper-magnesium alloy contact wire and its preparation process provided by the present invention are simultaneously applicable to the preparation of copper-magnesium alloy stranded wires (load-carrying cables) for high-speed railways with a speed of 400 - 450 km / h.

[0069] Examples of the high-strength copper-magnesium alloy contact wire for high-speed railways provided by the present invention:

[0070] The high-strength copper-magnesium alloy contact wire for high-speed railways includes Mg (magnesium), Cu (copper), and P (phosphorus). It uses cathode copper and magnesium ingots as raw materials. By mass percentage, the chemical composition of the copper-magnesium alloy contact wire includes: Mg: 0.40 - 0.70%, P: ≤0.01%. Other elements except Mg, P, and Cu are classified as impurities, and their total amount ≤0.10%. The balance is Cu.

[0071] Among them, by mass percentage, in cathode copper, Cu: ≥99.95%, and in magnesium ingot, Mg: 99.995%.

[0072] Based on the above description in this specification, those skilled in the art can also understand the following terms used, such as the terms indicating orientation or positional relationship, such as "upper", "lower", "front", "rear", "left", "right", "width", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationship shown in the drawings of this specification. It is only for the purpose of facilitating the description of the solution of the present invention and simplifying the description, rather than explicitly or implicitly indicating that the device or component involved must have the specific orientation, be constructed and operated in the specific orientation. Therefore, the above terms of orientation or positional relationship cannot be understood or interpreted as a limitation to the solution of the present invention.

[0073] In addition, in the description of this specification, the meaning of "a plurality of" is at least two, such as two, three or more, etc., unless otherwise specifically and clearly defined.

Claims

1. A preparation process for a high-strength copper-magnesium alloy contact wire for high-speed railways, characterized in that, It includes the following steps: S1: Prepare materials: According to the chemical composition ratio of the copper-magnesium alloy catenary, calculate the consumption of cathode copper and magnesium ingots and prepare materials according to the calculation results. S2: Melting and upward continuous casting: Hang the cathode copper at a distance d from the furnace mouth of the crucible furnace for baking to remove the moisture on the cathode copper. The baking time is t. Put the baked cathode copper into the crucible furnace for melting in batches. After the cathode copper melts, put in the magnesium ingots and stir, and add a covering agent on the surface of the copper liquid. Compressed gas is filled in the crucible furnace. Then, cool through the crystallizer and draw through the traction device to obtain a copper-magnesium alloy casting rod. The temperature of the copper liquid during melting is 1170 - 1210 °C, the upward drawing temperature is 1170 - 1210 °C, the traction speed is 200 - 500 mm / min, the depth of the crystallizer inserted into the melt is 160 - 310 mm, the water inlet temperature of the crystallizer is 25 - 50 °C, the pressure range of the compressed gas is 0.4 - 0.8 MPa. The covering agent is baked for at least 2.5 h before entering the furnace. The covering thickness of the covering agent on the copper liquid is not less than 100 mm. Clean the covering agent every 8 h. The oxygen content of the copper-magnesium alloy casting rod is controlled below 5 ppm. S3: Preheat: Take a copper-magnesium alloy casting rod of 1800 - 2400 mm and break it evenly into 6 - 8 pieces. Use a precision high-temperature forced-air oven to preheat it to a temperature of 680 ± 10 °C. S4: Continuous extrusion: First, preheat the surface of the extrusion wheel in the continuous extruder, and then introduce the preheated 6 - 8 copper-magnesium alloy casting rods into the continuous extruder for extrusion to obtain an extrusion rod with a diameter of 26 - 28 mm. The extrusion stress σ of the extruder ≥ 1000 MPa, the extrusion temperature is 550 - 580 °C, the extrusion waste rate is 5.5 - 7.5%, the overflow gap is 0.65 - 0.85 mm, the main shaft rotation speed of the extruder is 4 - 4.5 rpm, the working surface of the plug in the extruder is a curved surface, and the radius of curvature is 36 ± 1 mm. S5: Multi-pass drawing: Introduce the extrusion rod into the drawing equipment and perform drawing successively through multiple drawing dies arranged at intervals from front to back in the drawing equipment to obtain a copper-magnesium alloy contact wire with a cross-section of 150 mm 2 and the radial dimension of the die holes of the multiple drawing dies decreases successively from front to back.

2. The preparation process of the high-strength copper-magnesium alloy catenary for high-speed railways according to claim 1, wherein, In step S2, the diameters of the obtained copper-magnesium alloy casting rods by drawing are 20 mm, 25 mm, and 30 mm.

3. The preparation process of the high-strength copper-magnesium alloy catenary for high-speed railways according to claim 1 or 2, characterized in that, In step S5, a limiting structure is installed in front of the inlet of each drawing die to limit the degree of freedom of the extrusion rod. The limiting gap of the limiting structure is 3 - 8 mm.

4. The preparation process of the high-strength copper-magnesium alloy catenary for high-speed railways according to claim 1 or 2, characterized in that, The die entrance angle of the drawing die at the very front end of the drawing equipment is 18°, and the die entrance angles of the drawing dies in the drawing equipment decrease successively from front to back.

5. The preparation process of the high-strength copper-magnesium alloy catenary for high-speed railways according to claim 4, characterized in that, The die entrance angle of each drawing die is 1 - 1.5° smaller than that of the previous drawing die.

6. The preparation process of the high-strength copper-magnesium alloy catenary for high-speed railways according to claim 1 or 2, characterized in that, In step S5, the concentration of the cooling grease in the drawing die is 16 - 18%, and an extrusion rod cooling structure is provided on the drawing die. The concentration of the cooling grease in the extrusion rod cooling structure is 12 - 15%.

7. The preparation process of the high-strength copper-magnesium alloy catenary wire for high-speed railways according to claim 1 or 2, characterized in that In step S2, the hanging distance d is 10 - 30 cm, and the baking time t is greater than or equal to 10 min.

8. The preparation process of the high-strength copper-magnesium alloy catenary for high-speed railways according to claim 1 or 2, characterized in that, In step S2, the covering agent is carbon black or graphite powder or charcoal.

9. A high-strength copper-magnesium alloy catenary wire for high-speed railways, comprising Mg, Cu and P, characterized in that, Prepared by the preparation process of the high-strength copper-magnesium alloy catenary for high-speed railways according to any one of claims 1 to 8, using cathode copper and magnesium ingots as raw materials, by mass percentage, the chemical composition of the copper-magnesium alloy catenary includes: Mg: 0.40 to 0.70%, P: ≤0.01%, other elements except Mg, P and Cu are classified as impurities, and the total amount thereof is ≤0.10%, and the balance is Cu.

10. The high-strength copper-magnesium alloy contact wire for high-speed railways according to claim 9, characterized in that, By mass percentage, in the cathode copper, Cu: ≥99.95%, and in the magnesium ingot, Mg: 99.995%.

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