Preparation method of a high-conductivity and high-strength copper alloy moving-end conducting cylinder

Abstract

The invention discloses a preparation method of a high-conductivity and high-strength copper alloy moving-end conductive cylinder, which comprises the following steps: batching: by mass percentage: 0.15-0.35% chromium, 0.05-0.1% rare earth La, and the balance is copper; charging into a furnace for melting, casting, forging, sawing, extrusion molding, solution treatment, aging treatment, shot peening treatment, machining, and surface treatment. The copper-chromium alloy moving-end conductive cylinder prepared by the method of the invention has properties such as high conductivity, high strength, and high temperature resistance, reduces the deformation of the conductive cylinder during use, and improves the service life. The invention also provides an extrusion die used for preparing the copper-chromium alloy moving-end conductive cylinder, which improves the material utilization rate and reduces the production cost.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of the moving end conducting cylinder of copper-chromium alloy, and specifically relates to a preparation method of a high-conductivity and high-strength copper alloy moving end conducting cylinder. Background Art

[0002] The circuit breaker is one of the main electrical equipment in the substation. It can not only cut off and connect high-voltage lines and various no-load and load currents during the normal operation of the system, but also automatically, quickly and reliably cut off various overload currents and short-circuit currents through the action of the relay protection device when a fault occurs in the system, preventing the occurrence and expansion of the accident range.

[0003] In traditional circuit breakers, medium-pressure cylinders and moving end conducting cylinders are all thin-walled parts. Most of the materials are aluminum alloy and pure copper. The aluminum alloy material has poor electrical conductivity, only about 50% of that of the pure copper material; the pure copper material has high conductivity, but its hardness and strength are not high. Generally, cold-drawn tube materials or cold-extruded blanks are used for processing, with the overall hardness between HB80-100 and the tensile strength of 300 MPa.

[0004] Due to the too low conductivity of the aluminum alloy material for the conducting cylinder, the same cross-sectional size cannot meet the requirements for resistance during the use of the circuit breaker. If it is to be used, the cross-sectional size needs to be increased, and the structure of the circuit breaker will increase. For the conducting cylinder made of pure copper material, due to its low overall hardness, mechanical properties and high-temperature resistance, the conducting cylinder is extremely easy to deform during the movement and use of the circuit breaker. Summary of the Invention

[0005] Aiming at the problems pointed out in the above background art, the present invention provides a preparation method of a high-conductivity and high-strength copper alloy moving end conducting cylinder.

[0006] To solve the above technical problems, the technical solution of the present invention is as follows:

[0007] A preparation method of a high-conductivity and high-strength copper alloy moving end conducting cylinder includes the following steps:

[0008] S1. Batching:

[0009] By mass percentage: 0.15-0.35% chromium, 0.05-0.1% rare earth La, and the balance is copper;

[0010] S2. Charging and melting:

[0011] Charge the raw materials of step S1 into the furnace, and use a non-vacuum intermediate frequency induction furnace with electromagnetic stirring for melting. The melting temperature is 1100-1250 °C to melt the copper-chromium raw materials to obtain a melt;

[0012] S3. Casting:

[0013] After pouring the melt into the chute using a mold, promptly open the atmosphere protection for the chute and the furnace mouth to ensure a stable liquid level in the chute without interruption or overflow. Start casting when the melt reaches one-third of the mold volume, with an initial casting speed of 50 mm / min. When the melt flows into 75 - 85% of the mold volume, start electromagnetic stirring, set the frequency to 3 - 10 Hz and the current to 60 - 100 A, and slowly adjust the casting speed to 100 mm / min, with mechanical vibration at 30 times per minute. When all the melt in the melting furnace is poured into the chute, maintain the casting speed at 100 mm / min until casting is completed to obtain an alloy ingot.

[0014] S4. Forging:

[0015] Load the ingot into a resistance furnace, heat it to 850 °C, and hold for 30 ± 5 min. After the material is heated evenly, perform open-die forging, upset and roll round or draw out and swing round according to the size requirements, with the single deformation amount controlled within 60%, and forge it into a φ100*L bar.

[0016] S5. Sawing:

[0017] Use an automatic sawing machine to saw it off, with the sawing length L = 65 mm to obtain a blank.

[0018] S6. Extrusion forming:

[0019] Subject the blank obtained in step S5 to hot extrusion or warm extrusion or cold extrusion forming treatment to obtain an extruded blank.

[0020] S7. Solution treatment:

[0021] Place the extruded blank obtained in step S6 flat and evenly in a material frame, load it into a UBE600 type quenching furnace for solution treatment.

[0022] S8. Aging treatment:

[0023] Put the blank after solution treatment into an aging furnace, hold at 485 ± 10 °C for 4 hours, and air cool with the furnace for aging treatment.

[0024] S9. Shot peening:

[0025] Hang the blank after aging treatment evenly on a fixture and perform shot peening on the surface. The purpose is to remove the oxide scale, extrusion and heat treatment hardened layers on the product surface, reduce the surface hardness of the blank, and improve the cutting performance and tool life.

[0026] S10. Machining:

[0027] Perform turning and milling according to the product drawing. This conductive cylinder product belongs to a thin-walled part product, and it is very easy to deform during the machining process. Therefore, the key point during the machining process is to ensure the dimensional accuracy and prevent deformation.

[0028] S11. Surface treatment:

[0029] Perform silver plating on the overall surfaces of the inner hole and outer circle of the product after machining in step S10, and thus obtain the high-conductivity and high-strength copper alloy moving-end conductive cylinder.

[0030] Further, in the above solution, in step S2, during the melting process, after the copper melt is melted and clarified, when the measured temperature is 1150 ± 10 °C, take a sample with a graphite crucible to detect the Cr content, and adjust the melt composition according to the detection result until the chromium content reaches the target value; adjust the melt composition according to the detection result until the chromium content reaches the target value; while melting, blow argon into the melt surface for 15 min, and keep the argon pressure at 7 Pa to remove hydrogen in the melt; the electromagnetic stirring power is 800 KW ± 10 KW, and the electromagnetic stirring time is 15 min.

[0031] Further, in the above solution, in step S3, before casting, adjust the cooling water flow rate of the mold to 6.0 - 8.0 m 3 / h, during the casting process, adjust the cooling water flow rate of the mold to 30 - 35 m 3 / h, the cooling water temperature is 20 - 40 °C, ensure that the ingot is bright red when it is drawn out, and keep the ingot bright red during the casting process. Drain the casting well water before casting to avoid cold cracking due to sudden cooling, and timely clean the floating slag in the mold.

[0032] Further, in the above solution, while the mold is water-cooled, spray water on the ingot pulled out after solidification at a certain angle for secondary cooling. "Hot top casting" can be realized inside the mold, reducing the solidification rate of the upper melt, ensuring timely feeding, and at the same time facilitating the floating and removal of molten slag and gas. When the amount of melt in the crucible of the melting furnace is small, adjust the downward drawing speed to decrease until it stops. After the ingot is completely solidified, turn off the cooling water.

[0033] Further optionally, in the above solution, in step S6, the hot extrusion method is as follows: Load the blank into a box-type resistance furnace, raise the furnace temperature to 980°C ± 10°C, keep it warm for 30 minutes to ensure uniform heating of the blank; before the first extrusion, heat the die to 300°C for preheating; use a water-based environmentally friendly graphite lubricant to lubricate the surface of the punch and the die cavity; put the heated blank into the die, and extrude it into shape with a 1000T hydraulic press. The extrusion pressure is maintained at 15 - 20 Mpa, the extrusion speed is 15 - 20 mm / s, the pressure holding time is ≥ 2 s. After extrusion forming, open the die and eject the blank; The die used for hot extrusion is designed as follows: The blank has a machining allowance of 2.5 mm on each side according to the inner hole and outer shape dimensions. The coaxiality of the inner hole and the outer shape is designed to be within φ0.5. The die cavity size of the female die is designed according to 1.03 times the outer shape size of the blank, and the working size of the punch is the same as the inner cavity size of the blank; The materials of the punch and the female die of the die are selected as H13 hot work die steel, and the quenching hardness is HRC55 - 60.

[0034] Further optionally, in the above solution, in step S6, the warm extrusion method is as follows: Load the blank into a box-type resistance furnace, raise the furnace temperature to 400°C ± 10°C, keep it warm for 60 minutes to ensure uniform heating of the blank; before the first extrusion, heat the die to 300°C for preheating; use a water-based environmentally friendly graphite lubricant to lubricate the surface of the punch and the die cavity; put the heated blank into the die, and extrude it into shape with a 1000T hydraulic press. The extrusion pressure is maintained at 18 - 23 Mpa, the extrusion speed is 15 - 20 mm / s, the pressure holding time is ≥ 3 s. After extrusion forming, open the die and eject the blank; The die used for warm extrusion is designed as follows: The blank has a machining allowance of 2.5 mm on each side according to the inner hole and outer shape dimensions. The coaxiality of the inner hole and the outer shape is designed to be within φ0.5. The die cavity size of the female die is designed according to 1.03 times the outer shape size of the blank, and the working size of the punch is the same as the inner cavity size of the blank. The materials of the punch and the female die of the die are selected as H13 hot work die steel, and the quenching hardness is HRC55 - 60.

[0035] Further optionally, in the above solution, in step S6, the cold extrusion method is as follows: First, load the blank into a quenching furnace, heat it to 985°C ± 10°C, hold for 2 hours, and perform quenching treatment; immerse the quenched blank in vegetable oil, evenly apply it on the surface, put it into a mold for extrusion molding, keep the extrusion pressure at 20 - 25 Mpa, the extrusion speed is: 15 - 20 mm / s, the pressure holding time ≥ 3 s, perform extrusion molding, open the mold, and eject the blank; the mold used for cold extrusion is designed as follows: The blank leaves a machining allowance of 1.5 mm on one side according to the inner hole and outer shape dimensions, and the coaxiality of the inner hole and the outer shape is designed to be within φ0.3; the size of the die cavity is the same as the outer shape dimension of the blank, the working size of the punch is the same as the inner cavity dimension of the blank, and the materials of the punch and die of the mold are selected as M42 cold work die steel material, and the quenching hardness is HRC55 - 60.

[0036] Further, in the above solution, in step S7, the process parameters of the solution treatment are: Start timing when the furnace temperature rises to 985°C, hold for 1 - 1.5 hours, the cooling time is 5 min, and the draining time is 2 min.

[0037] Further, in the above solution, in step S10, the specific process of turning and milling is: rough turning - expanding inner hole turning process 1 - expanding inner hole turning process 2 - expanding inner hole milling process. By designing and manufacturing an inner hole expanding tire type clamping tooling, the product processing problem and the deformation problem during the processing process can be solved.

[0038] Further, in the above solution, in step S11, the silver plating thickness is 4 - 6 μm, which can prevent surface oxidation, increase wear resistance, and improve electrical conductivity.

[0039] Compared with the prior art, the beneficial effects of the present invention are reflected in the following aspects:

[0040] First, the copper - chromium alloy moving - end conductive cylinder prepared by the method of the present invention has properties such as high electrical conductivity, high strength, and high temperature resistance, reduces the deformation of the conductive cylinder during use, and improves the service life.

[0041] Second, the present invention also provides an extrusion mold for preparing the copper - chromium alloy moving - end conductive cylinder, which improves the material utilization rate and reduces the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is the extrusion blank drawing of Embodiment 1 of the present invention;

[0043] Figure 2 It is the assembly schematic diagram of the die, punch and product of Embodiment 1 of the present invention;

[0044] Figure 3 It is the structural schematic diagram of the punch of Embodiment 1;

[0045] Figure 4 It is a schematic structural view of the female die in Embodiment 1. Among them, a is the sectional three-dimensional front view of the female die, and b is the sectional three-dimensional side view of the female die;

[0046] Figure 5 It is a schematic structural view of the high-conductivity and high-strength copper alloy moving-end conductive cylinder product prepared in Embodiment 1;

[0047] Figure 6 It is the metallographic structure diagram of the material of the high-conductivity and high-strength copper alloy moving-end conductive cylinder product prepared in Embodiment 2. Among them, a is magnified 100 times (unetched), and b is magnified 500 times (unetched). Detailed implementation manners

[0048] Embodiment 1

[0049] A preparation method of a high-conductivity and high-strength copper alloy moving-end conductive cylinder includes the following steps:

[0050] S1. Batching:

[0051] By mass percentage: 0.19% chromium, 0.05% rare earth La, and the balance is copper; the rare earth La is wrapped with copper sheets;

[0052] S2. Furnace charging and melting:

[0053] Charge the raw materials in step S1 into the furnace, and then successively charge a flux (calcium fluoride: sodium fluoride = 1:1) and a covering agent (glass). Use a non-vacuum intermediate frequency induction furnace with electromagnetic stirring for melting. The melting temperature is 1100 °C to melt the copper-chromium raw materials to obtain a melt;

[0054] During the melting process, after the copper water is melted and clarified, take a sample with a graphite crucible to detect the Cr content, and adjust the melt composition according to the detection results until the chromium content reaches the target value; during melting, blow argon into the melt surface for 15 min, and keep the argon pressure at 7 Pa to remove hydrogen in the melt; the electromagnetic stirring power is 790 KW, and the electromagnetic stirring time is 15 min;

[0055] S3. Casting:

[0056] After pouring the melt into the chute using a crystallizer, promptly open the atmosphere protection for the chute and the furnace mouth to ensure a stable liquid level in the chute without interruption or overflow. Start casting when the melt reaches one-third of the volume height of the crystallizer, with an initial casting speed of 50 mm / min. When the melt flows into 75% of the volume of the crystallizer, turn on the electromagnetic stirring, set the frequency to 3 Hz and the current to 60 A, and slowly adjust the casting speed (the entire process of increasing the casting speed takes 10 minutes) to 100 mm / min, and perform mechanical vibration 30 times per minute. When all the melt in the melting furnace is poured into the chute, keep the casting speed at 100 mm / min until casting is completed to obtain an alloy ingot.

[0057] Before casting, adjust the cooling water flow rate of the crystallizer to 6.0 m 3 / h. During casting, adjust the cooling water flow rate of the crystallizer to 30 m 3 / h, with the cooling water temperature at 20 °C, ensure that the ingot remains bright red when it is drawn out, and the ingot remains bright red during the casting process. Drain the casting well water before casting to avoid cold cracking due to sudden cooling, and promptly clean the floating slag in the crystallizer.

[0058] While the crystallizer is water-cooled, spray water at a certain angle on the ingot pulled out after solidification for secondary cooling. "Hot top casting" can be achieved inside the crystallizer, reducing the solidification rate of the upper melt, ensuring timely feeding, and facilitating the floating and removal of molten slag and gas. When the amount of melt in the crucible of the melting furnace is small, adjust the downward drawing speed to decrease until it stops. After the ingot is completely solidified, turn off the cooling water.

[0059] S4. Forging:

[0060] Load the ingot into a resistance furnace, heat it to 850 °C, and hold for 25 minutes. After the material is heated evenly, perform free forging, upset and roll or draw and swing according to the size requirements, with the primary deformation amount controlled within 60%, and forge it into a φ100*L bar.

[0061] S5. Sawing:

[0062] Use an automatic sawing machine to saw it off, with the sawing length L = 65 mm to obtain a blank.

[0063] S6. Extrusion forming:

[0064] Subject the blank obtained in step S5 to hot extrusion treatment to obtain an extruded blank (as Figure 1 shown).

[0065] The method of hot extrusion is as follows: Load the blank into a box-type resistance furnace, raise the furnace temperature to 970 °C, keep it warm for 30 minutes to ensure uniform heating of the blank; before the first extrusion, preheat the die to 300 °C; lubricate the surface of the punch and the die cavity with a water-based environmentally friendly graphite lubricant; put the heated blank into the die, and use a 1000T hydraulic press to extrude and form. The extrusion pressure is maintained at 15 Mpa, the extrusion speed is 15 mm / s, the pressure holding time is 2 s, and after extrusion and forming, open the die and eject the blank; the die used for hot extrusion is designed as follows: The blank leaves a machining allowance of 2.5 mm on one side according to the inner hole and outer shape dimensions, and the coaxiality of the inner hole and the outer shape is designed to be within φ0.5. The size of the die cavity of the female die is designed according to 1.03 times the outer shape dimension of the blank, and the working size of the punch is the same as the inner cavity dimension of the blank; The materials of the punch and the female die of the die are selected as H13 hot work die steel materials, and the quenching hardness is HRC55 - 60. The structure of the extrusion die is as Figures 2 - 4 shown, where Figure 2 is the assembly schematic diagram of the female die, the punch and the product, Figure 3 is the structural schematic diagram of the punch, Figure 4 is the structural schematic diagram of the female die.

[0066] S7. Solution treatment:

[0067] Put the extruded blank obtained in step S6 flat and evenly into a material frame, load it into a UBE600 type quenching furnace for solution treatment; the process parameters of the solution treatment are: start timing when the furnace temperature rises to 985 °C, keep it warm for 1 hour, the cooling time is 5 min, and the draining time is 2 min;

[0068] S8. Aging treatment:

[0069] Put the blank after solution treatment into a BTF600 type aging furnace, keep it warm at 475 °C for 4 hours, and cool it in the furnace to carry out aging treatment;

[0070] S9. Shot peening treatment:

[0071] Hang the blank after aging treatment evenly on the fixture and perform shot peening treatment on the surface; the purpose is to remove the oxide scale, extrusion and heat treatment hardened layer on the product surface, reduce the surface hardness of the blank, and improve the cutting performance and tool life;

[0072] S10. Machining:

[0073] Carry out turning and milling according to the product drawing. This conductive cylinder product belongs to a thin-walled part product, and it is very easy to deform during the processing. Therefore, the key point during the processing is to ensure the dimensional accuracy and prevent deformation;

[0074] The specific processes of turning and milling are as follows: rough turning - expanding inner hole turning process 1 - expanding inner hole turning process 2 - expanding inner hole milling process; by designing and manufacturing an inner hole expanding mandrel clamping tooling, the product processing problems and deformation problems during the processing can be solved;

[0075] S11. Surface treatment:

[0076] The inner hole and the overall outer surface of the product after machining in step S10 are subjected to silver plating treatment, and the silver plating thickness is 4μm, which can prevent surface oxidation, increase wear resistance, improve conductivity, and finally obtain a high-conductivity and high-strength copper alloy moving-end conductive cylinder (the schematic structural diagram is as Figure 5 shown).

[0077] Example 2

[0078] A preparation method of a high-conductivity and high-strength copper alloy moving-end conductive cylinder includes the following steps:

[0079] S1. Batching:

[0080] By mass percentage: 0.2% chromium, 0.06% rare earth La, and the balance is copper; the rare earth La is wrapped with copper skin;

[0081] S2. Furnace charging and melting:

[0082] The raw materials in step S1 are charged into the furnace, and then flux (calcium fluoride: sodium fluoride = 1:1) and covering agent (glass) are loaded in sequence. Melting is carried out by a non-vacuum intermediate frequency induction furnace with electromagnetic stirring. The melting temperature is 1150°C to melt the copper-chromium raw materials and obtain a melt;

[0083] During the melting process, after the copper water is melted and clarified, when the temperature is measured at 1150°C, a sample is taken with a graphite crucible to detect the Cr content, and the melt composition is adjusted according to the detection results until the chromium content reaches the target value; during melting, argon is blown into the melt surface for 15 minutes, and the argon pressure is maintained at 7 Pa to remove hydrogen in the melt; the electromagnetic stirring power is 800 KWKW, and the electromagnetic stirring time is 15 minutes;

[0084] S3. Casting:

[0085] After pouring the melt into the chute using a mold, promptly open the atmosphere protection for the chute and the furnace mouth to ensure a stable liquid level in the chute without interruption or overflow. Start casting when the melt reaches one-third of the volume of the mold, with an initial casting speed of 50 mm / min. When the melt flows into 80% of the volume of the mold, start electromagnetic stirring, set the frequency to 6 Hz and the current to 80 A, and slowly adjust the casting speed (the entire process of increasing the casting speed takes 20 minutes) to 100 mm / min, and perform mechanical vibration 30 times per minute. When all the melt in the melting furnace is poured into the chute, maintain the casting speed at 100 mm / min until casting is completed to obtain an alloy ingot.

[0086] Before casting, adjust the cooling water flow rate of the mold to 7.0 m 3 / h. During casting, adjust the cooling water flow rate of the mold to 35 m 3 / h, with the cooling water temperature at 35°C, ensure that the ingot remains bright red when it is drawn out, and the ingot remains bright red during the casting process. Drain the well water in the casting area before casting to avoid chill cracking, and promptly clean the scum in the mold.

[0087] While the mold is water-cooled, spray water at a certain angle on the ingot pulled out after solidification for secondary cooling. "Hot top casting" can be achieved inside the mold, reducing the solidification rate of the upper melt, ensuring timely feeding, and at the same time facilitating the floating and removal of slag and gas. When the amount of melt in the crucible of the melting furnace is small, adjust the downward drawing speed to decrease until it stops. After the ingot is completely solidified, turn off the cooling water.

[0088] S4. Forging:

[0089] Load the ingot into a resistance furnace, heat it to 850°C, and hold for 32 minutes. After the material is heated evenly, perform free forging, upset and roll or draw and swing according to the size requirements, with the primary deformation amount controlled within 60%, and forge it into a φ100*L bar.

[0090] S5. Sawing:

[0091] Use an automatic sawing machine to saw it off, with the sawing length L = 65 mm to obtain a blank.

[0092] S6. Extrusion forming:

[0093] Subject the blank obtained in step S5 to warm extrusion forming treatment to obtain an extruded blank.

[0094] The method of warm extrusion is as follows: Load the blank into a box-type resistance furnace, raise the furnace temperature by 400 °C, keep it warm for 60 minutes to ensure uniform heating of the blank; Before the first extrusion, preheat the mold to 300 °C; Use a water-based environmentally friendly graphite lubricant to lubricate the surface of the punch and the die cavity; Put the heated blank into the mold, and use a 1000T hydraulic press to extrude and form. The extrusion pressure is maintained at 18 Mpa, the extrusion speed is 20 mm / s, the holding pressure time is 5 s, after extrusion and forming, open the mold and eject the blank; The mold used for warm extrusion is designed as follows: The blank is designed with a machining allowance of 2.5 mm on one side for the inner hole and outer shape dimensions, and the coaxiality of the inner hole and the outer shape is ensured to be within φ0.5. The die cavity size of the concave die is designed according to 1.03 times the outer shape size of the blank, the working size of the punch is the same as the inner cavity size of the blank, and the materials of the punch and the concave die of the mold are selected as H13 hot work die steel material, and the quenching hardness is HRC55 - 60.

[0095] S7. Solution treatment:

[0096] Put the extruded blank obtained in step S6 flat and evenly into the material frame, load it into a UBE600 type quenching furnace for solution treatment; The process parameters of the solution treatment are: Start timing when the furnace temperature rises to 985 °C, keep it warm for 1.2 hours, the cooling time is 5 min, and the draining time is 2 min;

[0097] S8. Aging treatment:

[0098] Put the blank after solution treatment into a BTF600 type aging furnace, keep it warm at 490 °C for 4 hours, and cool it in the furnace with the air to carry out aging treatment;

[0099] S9. Shot peening treatment:

[0100] The blank after aging treatment is evenly hung on the fixture and the surface is subjected to shot peening treatment; The purpose is to remove the oxide scale, extrusion and heat treatment hardened layer on the product surface, reduce the surface hardness of the blank, and improve the cutting performance and tool life;

[0101] S10. Machining:

[0102] Carry out turning and milling according to the product drawing. This conductive cylinder product belongs to a thin-walled part product, and it is very easy to deform during the processing. Therefore, the key point during the processing is to ensure the dimensional accuracy and prevent deformation;

[0103] The specific process of turning and milling is: rough turning - expanding the inner hole turning process 1 - expanding the inner hole turning process 2 - expanding the inner hole milling process; By designing and making an inner hole expanding type clamping fixture, the product processing problem and the deformation problem during the processing can be solved;

[0104] S11. Surface treatment:

[0105] The inner hole and the overall surface of the outer circle of the product after machining in step S1 are silver-plated with a silver plating thickness of 5 μm, which can prevent surface oxidation, increase wear resistance and improve electrical conductivity. Finally, a high-conductivity and high-strength copper alloy moving-end conductive cylinder is obtained (the metallographic structure diagram of its material is as shown in Figure 6 shown).

[0106] Example 3

[0107] A preparation method of a high-conductivity and high-strength copper alloy moving-end conductive cylinder includes the following steps:

[0108] S1. Batching:

[0109] By mass percentage: 0.3% chromium, 0.065% rare earth La, and the balance is copper; the rare earth La is wrapped with copper skin;

[0110] S2. Furnace charging and melting:

[0111] Charge the raw materials in step S1 into the furnace, then successively charge the flux (calcium fluoride: sodium fluoride = 1:1) and the covering agent (glass), and use a non-vacuum intermediate frequency induction furnace with electromagnetic stirring for melting. The melting temperature is 1250 °C to melt the copper-chromium raw materials to obtain a melt;

[0112] During the melting process, after the copper liquid is melted and clarified, when the temperature is measured at 1160 °C, take a sample with a graphite crucible to detect the Cr content, and adjust the melt composition according to the detection results until the chromium content reaches the target value; during melting, blow argon into the melt surface for 15 minutes, and keep the argon pressure at 7 Pa to remove the hydrogen in the melt; the electromagnetic stirring power is 8010 KW, and the electromagnetic stirring time is 15 minutes;

[0113] S3. Casting:

[0114] Use a mold to pour the melt into the chute, and then immediately open the atmosphere protection chute and the furnace mouth to ensure that the liquid level in the chute is stable, without interruption or overflow; when the melt enters and reaches one-third of the volume of the mold, start casting, and the initial casting speed is 50 mm / min; when the melt flows into 85% of the volume of the mold, start electromagnetic stirring, set the frequency to 10 Hz and the current to 100 A, and slowly adjust the casting speed (the entire casting speed increase process takes 30 minutes) to 100 mm / min, and mechanically vibrate 30 times per minute; when all the melt in the melting furnace is poured into the chute, keep the casting speed at 100 mm / min until casting is completed to obtain an alloy ingot;

[0115] Before casting, adjust the cooling water flow rate of the mold to 8.0 m 3 / h, and during casting, adjust the cooling water flow rate of the mold to 35 m 3 / h, the cooling water temperature is 40 °C, ensuring that the ingot remains bright red when drawn out, and the ingot remains bright red during the casting process. Drain the casting well water before casting to avoid chill cracking, and promptly clean the scum in the mold;

[0116] While the mold is water-cooled, spray water at a certain angle on the ingot pulled out after solidification for secondary cooling. "Hot top casting" can be achieved inside the mold, reducing the solidification rate of the upper melt, ensuring timely feeding, and facilitating the floating and removal of molten slag and gas. When the amount of melt in the crucible of the melting furnace is small, adjust the downward drawing speed to decrease until it stops. After the ingot is completely solidified, turn off the cooling water;

[0117] S4. Forging:

[0118] Load the ingot into a resistance furnace, heat it to 850 °C, hold for 35 min. After the material is heated evenly, perform free forging. Upset and roll or stretch and swing according to the dimensional requirements, with the primary deformation amount controlled within 60%, and forge into a φ100*L bar;

[0119] S5. Sawing:

[0120] Use an automatic sawing machine to saw, with the sawing length L = 65 mm to obtain the blank;

[0121] S6. Extrusion forming:

[0122] Process the blank obtained in step S5 by cold extrusion forming to obtain the extruded blank;

[0123] The method of cold extrusion is as follows: First, load the blank into a quenching furnace, heat it to 995 °C, hold for 2 hours for quenching treatment; Immerse the quenched blank in vegetable oil, apply it evenly on the surface, put it into the mold for extrusion forming, with the extrusion pressure maintained at 25 Mpa, the extrusion speed: 20 mm / s, the pressure holding time 5 s, for extrusion forming, open the mold, and eject the blank; The mold used for cold extrusion is designed as follows: The blank leaves a machining allowance of 1.5 mm on one side according to the inner hole and outer shape dimensions, and the coaxiality of the inner hole and the outer shape is guaranteed to be within φ0.3 for design; The die cavity size of the female die is the same as the outer shape size of the blank, and the working size of the male die is the same as the inner cavity size of the blank. The materials of the male and female dies of the mold are selected as M42 cold work die steel materials, and the quenching hardness is HRC55 - 60.

[0124] S7. Solution treatment:

[0125] Place the extruded blank obtained in step S6 flat and evenly into the material frame, load it into a UBE600 type quenching furnace for solution treatment; The process parameters of the solution treatment are: Start timing when the furnace temperature rises to 985 °C, hold for 1.5 hours, the cooling time is 5 min, and the draining time is 2 min;

[0126] S8. Aging treatment:

[0127] Put the solution-treated blank into a BTF600 type aging furnace, keep it at 495 °C for 4 hours, and then air-cool it in the furnace for aging treatment;

[0128] S9. Shot peening treatment:

[0129] Hang the aged blank evenly on the fixture and conduct shot peening treatment on the surface; the purpose is to remove the oxide scale, extrusion and heat treatment hardened layer on the product surface, reduce the surface hardness of the blank, and improve the cutting performance and tool life;

[0130] S10. Machining:

[0131] Carry out turning and milling according to the product drawing. This conductive cylinder product belongs to a thin-walled part product, and it is very easy to deform during the processing. Therefore, the key point during the processing is to ensure the dimensional accuracy and prevent deformation;

[0132] The specific process of turning and milling is: rough turning - expanding inner hole turning process 1 - expanding inner hole turning process 2 - expanding inner hole milling process; by designing and manufacturing an inner hole expanding chuck type clamping tooling, the product processing problem and the deformation problem during the processing can be solved;

[0133] S11. Surface treatment:

[0134] Carry out silver plating treatment on the overall surface of the inner hole and outer circle of the product after machining in step S10. The silver plating thickness is 6 μm, which can prevent surface oxidation, increase wear resistance and improve conductivity, and finally obtain a high-conductivity and high-strength copper alloy moving-end conductive cylinder.

[0135] Take the product samples prepared in Examples 1 - 3 for composition and mechanical property tests. Sample 1 and Sample 2 are prepared by the method of Example 1, Sample 3 and Sample 4 are prepared by the method of Example 2, and Sample 5 and Sample 6 are prepared by the method of Example 3.

[0136] (1) The sampling test results of the material composition are shown in Table 1:

[0137] Table 1 Sampling test results of material composition

[0138]

[0139] (2) The test results of the material mechanical properties are shown in Table 2:

[0140] Table 2 Test results of material mechanical properties

[0141]

[0142] From Figure 6As can be seen from Table 1 and Table 2, the high-conductivity and high-strength copper alloy moving-end conductive cylinder material prepared by the method of the present invention has uniform composition, the conductivity of the material is >92% / IACS, the hardness HV>115, the tensile strength >400MPa, the softening temperature >400°C, and the overall performance of the material is excellent.

Claims

1. A preparation method of a high-conductivity and high-strength copper alloy moving-end conducting cylinder, characterized in that, It includes the following steps: S1. Batching: By mass percentage: 0.15 - 0.35% chromium, 0.05 - 0.1% rare earth La, and the balance is copper; S2. Charging and melting: Charge the raw materials of step S1 into the furnace, and use a non-vacuum medium-frequency induction furnace with electromagnetic stirring for melting. The melting temperature is 1100 - 1250 °C to melt the copper-chromium raw materials to obtain a melt; S3. Casting: Pour the melt into the chute using a mold, and immediately open the atmosphere protection chute and the furnace mouth after pouring. When the melt enters and reaches one-third of the height of the mold volume, start casting, and the initial casting speed is 50 mm / min; when the melt flows into 75 - 85% of the mold volume, turn on the electromagnetic stirring, set the frequency to 3 - 10 Hz, the current to 60 - 100 A, and slowly adjust the casting speed to 100 mm / min, and perform mechanical vibration 30 times per minute; when all the melt in the melting furnace is poured into the chute, keep the casting speed at 100 mm / min until casting is completed to obtain an alloy ingot; S4. Forging: Load the ingot into a resistance furnace, heat it to 850 °C, and keep it warm for 30 ± 5 min. After the material is heated evenly, perform free forging, upset and roll round or draw out and swing round according to the dimensional requirements, and control the single deformation amount within 60% to forge it into a φ100*L bar; S5. Sawing: Saw it off using an automatic sawing machine, and the sawing length L = 65 mm to obtain a blank; S6. Extrusion forming: Subject the blank obtained in step S5 to hot extrusion or warm extrusion or cold extrusion forming treatment to obtain an extruded blank; S7. Solution treatment: Evenly and flatly place the extruded blank obtained in step S6 into a material frame, load it into a quenching furnace, and perform solution treatment; S8. Aging treatment: Put the blank after solution treatment into an aging furnace, keep it warm at 485 ± 10 °C for 4 hours, and cool it in the furnace with the air to perform aging treatment; S9. Shot peening treatment: Evenly hang the blank after aging treatment on a fixture and perform shot peening treatment on the surface; S10. Machining: Perform turning and milling according to the product drawing; S11. Surface treatment: Perform silver plating on the overall surface of the inner hole and outer circle of the product after machining in step S10, and then a high-conductivity and high-strength copper alloy moving-end conductive cylinder is obtained; In step S2, during the melting process, after the copper melt is melted and clarified, when the measured temperature is 1150 ± 10 °C, take a sample with a graphite crucible to detect the Cr content, and adjust the melt composition according to the detection result until the chromium content reaches the target value; while melting, blow argon into the melt surface for 15 min, and keep the argon pressure at 7 Pa; In the step S3, before casting, the cooling water flow rate of the mold is adjusted to 6.0 - 8.0 m 3 / h, and during casting, the cooling water flow rate of the mold is adjusted to 30 - 35 m 3 / h, and the cooling water temperature is 20 - 40 °C; While the mold is water-cooled, spray water on the ingot pulled out after solidification for secondary cooling. When the amount of melt in the melting furnace crucible is small, adjust the downward drawing speed to decrease until it stops. After the ingot is completely solidified, turn off the cooling water; In step S6, the hot extrusion method is as follows: Load the blank into a box-type resistance furnace, raise the furnace temperature to 980°C ± 10°C, hold for 30 minutes to ensure uniform heating of the blank; before the first extrusion, preheat the die to 300°C; lubricate the surface of the punch and the die cavity with a water-based environmentally friendly graphite lubricant; put the heated blank into the die and extrude it into shape using a 1000T hydraulic press, with the extrusion pressure maintained at 15 - 20 Mpa, the extrusion speed being 15 - 20 mm / s, the pressure holding time ≥ 2 s, extrude it into shape, open the die, and eject the blank; In step S6, the warm extrusion method is as follows: Load the blank into a box-type resistance furnace, raise the furnace temperature to 400°C ± 10°C, hold for 60 minutes to ensure uniform heating of the blank; before the first extrusion, preheat the die to 300°C; lubricate the surface of the punch and the die cavity with a water-based environmentally friendly graphite lubricant; put the heated blank into the die and extrude it into shape using a 1000T hydraulic press, with the extrusion pressure maintained at 18 - 23 Mpa, the extrusion speed being 15 - 20 mm / s, the pressure holding time ≥ 3 s, extrude it into shape, open the die, and eject the blank; In step S6, the cold extrusion method is as follows: First, load the blank into a quenching furnace, heat it to 985°C ± 10°C, hold for 2 hours for quenching treatment; immerse the quenched blank in vegetable oil, apply it evenly on the surface, put it into the die and extrude it into shape, with the extrusion pressure maintained at 20 - 25 Mpa, the extrusion speed being 15 - 20 mm / s, the pressure holding time ≥ 3 s, extrude it into shape, open the die, and eject the blank.

2. The preparation method of a high-conductivity and high-strength copper alloy moving-end conductive cylinder according to claim 1, characterized in that, In step S7, the process parameters of the solution treatment are: Start timing when the furnace temperature rises to 985°C, hold for 1 - 1.5 hours, the cooling time is 5 min, and the draining time is 2 min.

3. The preparation method of a high-conductivity and high-strength copper alloy moving-end conductive cylinder according to claim 1, characterized in that, In step S10, the specific process of turning and milling is: Rough turning - Boring turning process 1 - Boring turning process 2 - Boring milling process.

4. The preparation method of a high-conductivity and high-strength copper alloy moving-end conducting cylinder according to claim 1, characterized in that, In step S11, the silver plating thickness is 4 - 6 μm.

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