A continuous casting and continuous rolling method for preparing a low-oxygen high-conductivity copper rod

Abstract

The application provides a continuous casting and continuous rolling preparation method of low-oxygen high-conductivity copper rod, and belongs to the technical field. The method comprises the following steps: detecting, smelting and heat preserving copper raw materials to form copper liquid with controlled temperature state and oxidation state; performing covering protection, smooth flow guiding and inclusion blocking treatment in the copper liquid transfer path to form low-oxygen low-inclusion copper liquid; matching the continuous casting conditions according to the temperature state and inclusion control state of the low-oxygen low-inclusion copper liquid and performing continuous casting to form hot casting blank with a temperature suitable for continuous rolling; performing surface state treatment and entry rolling temperature confirmation on the hot casting blank to form hot casting blank suitable for rolling; and performing continuous rolling, post-rolling cooling and cleaning, drying protection and winding on the hot casting blank suitable for rolling to form the low-oxygen high-conductivity copper rod.

Description

Technical Field

[0001] This invention belongs to the technical field, specifically relating to a continuous casting and rolling method for preparing low-oxygen, high-conductivity copper rods. Background Technology

[0002] Low-oxygen copper rods are mainly used in electrical engineering materials such as wires and cables, enameled wires, and conductive wires. The manufacturing goals of low-oxygen copper rods typically include low oxygen content, low resistivity, good wire drawing performance, and stable surface quality. Current low-oxygen copper rod manufacturing processes usually employ continuous casting and rolling. Electrolytic copper, cathode copper, partially recycled copper, or graded copper raw materials are melted into molten copper, which is then subjected to heat preservation, flow guiding, ladle casting, and continuous casting to form a copper billet. Subsequently, the residual heat of the billet is used for continuous rolling, followed by cooling, cleaning, drying, waxing, and winding to obtain a low-oxygen copper rod of a certain diameter.

[0003] Existing continuous casting and rolling processes for low-oxygen copper rods typically include raw material batching and smelting, copper melt treatment, continuous casting, continuous rolling, and post-processing. The raw material batching and smelting process reduces impurities entering the molten copper; the copper melt treatment process controls the oxygen and impurity content through methods such as covering and protection, oxidation to remove impurities, reduction, slag removal, and heat preservation; the continuous casting process controls the casting temperature, casting speed, and cooling conditions to solidify the molten copper into a billet; the continuous rolling process controls the entry temperature, rolling passes, reduction, rolling speed, and emulsion cooling and lubrication conditions to roll the billet into a copper rod of the target diameter; and the post-processing process improves the surface condition of the copper rod and facilitates storage and transportation through cleaning, cooling, drying, waxing, and winding. Existing continuous casting and rolling processes for low-oxygen copper rods can complete the basic preparation tasks from copper raw materials to finished low-oxygen copper rods and are suitable for continuous, high-volume production scenarios.

[0004] In further obtaining copper rods with stable low oxygen and high conductivity, existing continuous casting and rolling processes for low-oxygen copper rods still suffer from insufficient cross-stage coordination. During the process of molten copper entering the crystallization zone from the furnace via the ladle, trough, and nozzle, air contact, surface disturbance, temperature drop, oxide film rupture, and slag entrainment cause fluctuations in oxygen content and oxide inclusion status. Even molten copper that passes pre-casting inspection may still develop localized oxide inclusions or oxygen content fluctuations after entering the crystallization stage. During continuous casting, casting temperature, casting speed, cooling intensity, gas evolution, and impurity distribution collectively affect the formation of porosity, inclusions, shrinkage cavities, and cracks in the billet. Internal defects in the billet can affect subsequent rolling deformation and the conductivity of the copper rod. During continuous rolling and post-cooling treatment, the oxide scale, edge defects, inclusion distribution, and internal porosity of the billet surface affect the rolling deformation process. Oxide scale or copper powder may be carried or pressed into the copper rod surface, and localized defects may extend into linear defects during rolling deformation, thus affecting the surface cleanliness of the copper rod, the stability of subsequent wire drawing, and the consistency of conductivity. Summary of the Invention

[0005] This invention overcomes the shortcomings of the prior art and provides a continuous casting and rolling preparation method for low-oxygen, high-conductivity copper rods.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a method for continuous casting and rolling of low-oxygen, high-conductivity copper rods, comprising the following steps:

[0007] S1: The copper raw materials are batched, tested, smelted, and kept warm to form a copper liquid with controlled temperature and oxidation state;

[0008] S2: Covering protection, smooth flow guidance and inclusion blocking treatment are carried out in the copper liquid transfer path to form a low-oxygen and low-inclusion copper liquid;

[0009] S3: Based on the temperature state and inclusion control state of the low-oxygen, low-inclusion copper liquid, match the continuous casting conditions and carry out continuous casting to form a hot cast billet with a temperature suitable for continuous rolling.

[0010] S4: Perform surface condition treatment and confirm the rolling temperature for the hot-cast billet to form a suitable hot-cast billet for rolling.

[0011] S5: Utilizing suitable hot-cast billets for continuous rolling, followed by cooling, cleaning, drying, protection, and coiling, a low-oxygen, high-conductivity copper rod is formed.

[0012] Furthermore, in step S1, when testing the copper raw materials, the testing objects include the purity of the copper raw materials, the state of oil stains on the surface of the copper raw materials, the state of water accumulation on the surface of the copper raw materials, and the state of obvious non-copper foreign matter in the copper raw materials.

[0013] Furthermore, in step S1, the melting temperature is 1120℃ to 1200℃, the thickness of the covering layer during the melting stage is 20mm to 80mm, the slag removal treatment is carried out after the copper raw material is completely melted, the holding temperature is 1100℃ to 1160℃, the holding time is 10min to 60min, the oxygen content of the copper liquid before casting is controlled to be 100mg / kg to 400mg / kg, and the thickness of the covering layer during the holding stage is 20mm to 80mm.

[0014] Furthermore, in step S2, the copper liquid surface is covered and protected at the runner, ladle and nozzle, the copper liquid transfer temperature is 1080℃ to 1150℃, the thickness of the covering layer during the transfer stage is 20mm to 80mm, and the temperature drop in the copper liquid transfer path is no more than 40℃.

[0015] Furthermore, in step S2, the flow rate of the molten copper in the copper transfer path is 0.15 m / s to 0.80 m / s, the fluctuation range of the molten copper level in the flow channel is within ±10 mm, and the copper transfer path is equipped with slag-blocking, settling, and filtering positions. The settling residence time is 10 s to 60 s, the pore size of the filter element is 10 ppi to 40 ppi, the slag-blocking position is set before the inlet of the gating nozzle, and the oxygen content control target before the low-oxygen, low-inclusion copper liquid enters the continuous casting area is 100 mg / kg to 400 mg / kg.

[0016] Further, in step S3, the continuous casting conditions include casting temperature, casting speed, crystallization cooling water temperature and crystallization cooling water pressure. The casting temperature is 1080℃ to 1150℃, the casting speed is 6m / min to 18m / min, the crystallization cooling water temperature is 20℃ to 45℃, the crystallization cooling water pressure is 0.15MPa to 0.45MPa, and the crystallization cooling water flow rate is 20m³ / h to 80m³ / h.

[0017] Furthermore, in step S3, when the casting temperature is between 1120℃ and 1150℃, the casting speed is controlled between 6m / min and 12m / min; when the casting temperature is between 1080℃ and 1120℃, the casting speed is controlled between 10m / min and 18m / min.

[0018] Furthermore, in step S3, the fluctuation range of the copper liquid level in the crystallization region is within ±8mm, and the hot-cast billet exit temperature is 850℃ to 980℃.

[0019] Further, in step S4, the surface condition treatment is an online cleaning set between the outlet of the continuous casting device and the inlet of the continuous rolling mill. The online cleaning method includes airflow cleaning or mechanical brushing. The airflow cleaning pressure is 0.20MPa to 0.60MPa, the mechanical brushing speed is 500r / min to 2000r / min, and the inlet temperature is 750℃ to 950℃.

[0020] Further, in step S5, the continuous rolling inlet temperature is 750℃ to 950℃, the single-pass reduction rate is 10% to 35%, the rolling speed is 5m / s to 25m / s, the target copper rod diameter is 8.0mm ± 0.3mm, the cooling and lubricating medium temperature is 20℃ to 45℃, the emulsion mass concentration is 1.0% to 4.0%, the cooling and lubricating medium pressure is 0.20MPa to 0.60MPa, the post-rolling cooling water temperature is 20℃ to 45℃, the post-rolling cleaning pressure is 0.20MPa to 0.80MPa, the surface temperature of the cooled copper rod is 40℃ to 90℃, the drying air pressure is 0.20MPa to 0.60MPa, the surface protective agent coating amount is 0.02g / m to 0.10g / m, and the winding tension is 50N to 300N.

[0021] This invention addresses the shortcomings of the prior art and has the following beneficial effects:

[0022] This invention relates to the continuous casting and rolling process for producing low-oxygen, high-conductivity copper rods. The copper molten material is protected by covering, guided smoothly, and has inclusion-blocking mechanisms along its transport path, ensuring the copper molten material entering the continuous casting zone is in a low-oxygen, low-inclusion state. Continuous casting conditions are matched to the temperature and inclusion control of the low-oxygen, low-inclusion copper molten material, allowing it to form a hot-cast billet with a temperature suitable for continuous rolling under controlled casting temperature, casting speed, and crystallization cooling conditions. Pre-rolling surface condition treatment, entry temperature confirmation, continuous rolling, post-rolling cooling and cleaning, drying and protection, and coiling continuously constrain the surface material, entry temperature, rolling deformation, and post-rolling surface residue of the hot-cast billet. Through the coordinated control of copper molten material transport, continuous casting matching, and post-rolling treatment, the mismatch between the copper molten oxidation state, billet defect formation, and rolling microstructure evolution is reduced, maintaining a correspondence between the low-oxygen state and electrical conductivity during the continuous preparation process.

[0023] In step S2 of this invention, a combination of covering protection, smooth flow guidance, and inclusion blocking is used in the copper liquid transfer path. The copper liquid transfer temperature is limited to 1080℃ to 1150℃, the covering layer thickness during the transfer stage is 20mm to 80mm, the temperature drop in the copper liquid transfer path is no greater than 40℃, the copper liquid flow rate is 0.15m / s to 0.80m / s, the copper liquid level fluctuation range in the flow channel is within ±10mm, the settling residence time is 10s to 60s, the filter element pore size is 10ppi to 40ppi, and the slag-blocking position is located before the pouring nozzle inlet. Covering protection reduces the contact between the copper liquid surface and air, smooth flow guidance restricts oxide film rupture and slag entrapment, and slag blocking, settling, and filtration block, float, or trap slag, oxide film, and particle inclusions before the continuous casting zone inlet. Test results show that after adopting a combination of covering protection, stable flow guidance, slag blocking, settling and filtration for transfer control, the oxygen content of the finished copper rod and the area ratio of internal defects in the billet are in a lower range compared with conventional transfer control, indicating that the fluctuation of oxidation state and the entry of inclusions are constrained during the copper liquid transfer stage.

[0024] In step S3 of this invention, continuous casting conditions are matched based on the temperature state and inclusion control state of the low-oxygen, low-inclusion copper liquid, and the casting temperature is limited to 1080℃ to 1150℃, the casting speed to 6m / min to 18m / min, the crystallization cooling water temperature to 20℃ to 45℃, the crystallization cooling water pressure to 0.15MPa to 0.45MPa, and the crystallization cooling water flow rate to 20m³ / h to 80m³ / h. A corresponding control relationship is further established between the casting temperature and the casting speed, limiting the copper liquid level fluctuation range in the crystallization region to within ±8mm, and the hot-cast billet exit temperature to 850℃ to 980℃. This matching of continuous casting conditions ensures that the liquid supply state in the crystallization region, the solidification front state, the solidification shell formation state, and the hot-cast billet exit thermal state are all subject to joint constraints, enabling the low-oxygen, low-inclusion copper liquid to form a hot-cast billet with a temperature suitable for continuous rolling during the solidification process. The test results show that the preparation method with matching casting temperature, casting speed, crystallization cooling water pressure, hot billet exit temperature and rolling temperature has a lower internal defect area ratio, finished copper rod volume resistivity at 20℃ and finished copper rod surface defect number compared with the preparation method with low temperature side mismatch or high temperature side mismatch. This indicates that the mismatch between the solidification state and the hot state of continuous rolling in the continuous casting stage is reduced.

[0025] In step S4, this invention includes an online cleaning process located between the outlet of the continuous casting unit and the inlet of the continuous rolling mill. The online cleaning method is specified as either airflow cleaning or mechanical brushing. The airflow cleaning pressure is 0.20 MPa to 0.60 MPa, the mechanical brushing speed is 500 r / min to 2000 r / min, and the inlet temperature is 750°C to 950°C. In step S5, this invention specifies the continuous rolling inlet temperature, single-pass reduction rate, rolling speed, cooling and lubrication medium temperature, emulsion concentration, cooling and lubrication medium pressure, post-rolling cooling and cleaning, drying and protection, and coiling conditions. Online cleaning removes or blocks loose oxides, adhering particles, and surface contaminants on the hot-cast billet surface before it enters the rolling mill. The confirmed inlet temperature ensures the hot-cast billet enters the continuous rolling mill at a hot state of 750°C to 950°C. Continuous rolling and post-rolling treatment conditions continuously constrain the rolling deformation zone and the residual state of the copper rod surface. The test results show that the preparation method with surface condition treatment of hot-cast billets and continuous rolling cooling control, compared with the conventional method that does not set online cleaning of hot-cast billet surface and mainly relies on post-rolling cooling cleaning, has a lower number of surface defects and a lower volume resistivity of finished copper rods at 20℃. This indicates that the surface material intrusion, post-rolling residue and microstructure fluctuation of hot-cast billets are reduced.

[0026] Copper molten material transfer control limits the oxygen content, inclusion entry path, and temperature drop entering the continuous casting zone; continuous casting matching control targets the controlled copper molten material state, limiting casting temperature, casting speed, crystallization cooling conditions, and copper molten material level fluctuations in the crystallization zone to a range suitable for forming continuously rolled hot-cast billets; continuous rolling post-treatment control directly addresses the surface condition and entry temperature of the hot-cast billet, and limits surface material intrusion and residue through rolling, cooling, cleaning, drying, and protection. Copper molten material transfer control reduces inclusion sources and oxidation fluctuations, continuous casting matching control reduces solidification defect formation, and continuous rolling post-treatment control reduces defect propagation and surface residue. Test results show that when the copper liquid transfer parameters or the casting continuous rolling hot state parameters deviate from each other alone, the oxygen content, internal defect area ratio of the billet, volume resistivity of the finished copper rod at 20°C, or the number of surface defects of the finished copper rod increase. When the copper liquid transfer parameters and the casting continuous rolling hot state parameters are kept within the range defined in the claims, multiple indicators remain in the lower range. This indicates that the coordination between covering protection, stable flow guidance, inclusion blocking, matching of continuous casting conditions, hot billet surface condition treatment, confirmation of entry temperature, and post-continuous rolling treatment conditions can jointly reduce the deviation between low oxygen state, low defect billet state, and electrical conductivity of the finished copper rod. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a step-by-step diagram of a continuous casting and rolling process for preparing low-oxygen, high-conductivity copper rods.

[0029] Figure 2 This is a diagram illustrating the principle of low-oxygen, low-inclusion formation in the copper liquid transport path.

[0030] Figure 3 This is a flowchart of the hot state matching control for casting continuous rolling. Detailed Implementation

[0031] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein. Therefore, the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0032] Method implementation:

[0033] This embodiment provides a continuous casting and rolling method for producing low-oxygen, high-conductivity copper rods, specifically for rods formed from copper raw materials through smelting, copper molten material transfer, continuous casting, continuous rolling, and post-processing. During the continuous casting and rolling process, there is a continuous transmission relationship between the oxidation state of the copper molten material, the formation of defects in the cast billet, and the evolution of the rolling microstructure. To reduce the mismatch between these factors, this embodiment sets up sequential processing steps along the three continuous physical states of the copper molten material, the hot-cast billet, and the copper rod, ensuring that the low-oxygen state, low-inclusion state, suitable-for-rolling state of the cast billet, and the finished copper rod state are formed sequentially in the continuous production chain.

[0034] This embodiment forms a copper melt with controlled temperature and oxidation state after copper raw material smelting and heat preservation; a low-oxygen, low-inclusion copper melt is formed in the copper melt transfer path through covering protection, smooth flow guidance and inclusion blocking treatment; continuous casting conditions are matched according to the temperature state and inclusion control state of the low-oxygen, low-inclusion copper melt to form a hot-cast billet with a temperature suitable for continuous rolling; surface condition treatment and entry temperature confirmation are performed on the hot-cast billet before it enters the continuous rolling mill; continuous rolling, post-rolling cooling and cleaning, drying and protection and coiling are carried out using the suitable hot-cast billet.

[0035] like Figure 1 As shown, a continuous casting and rolling method for preparing low-oxygen, high-conductivity copper rods includes the following steps:

[0036] S1: The copper raw materials are batched, tested, smelted, and kept warm to form a copper liquid with controlled temperature and oxidation state;

[0037] S2: Covering protection, smooth flow guidance and inclusion blocking treatment are carried out in the copper liquid transfer path to form a low-oxygen and low-inclusion copper liquid;

[0038] S3: Based on the temperature state and inclusion control state of the low-oxygen, low-inclusion copper liquid, match the continuous casting conditions and carry out continuous casting to form a hot cast billet with a temperature suitable for continuous rolling.

[0039] S4: Perform surface condition treatment and confirm the rolling temperature for the hot-cast billet to form a suitable hot-cast billet for rolling.

[0040] S5: Utilizing suitable hot-cast billets for continuous rolling, followed by cooling, cleaning, drying, protection, and coiling, a low-oxygen, high-conductivity copper rod is formed.

[0041] The following description, in conjunction with the specific implementation process of each step, further explains the method so that those skilled in the art can clearly understand the interrelationship of each step in implementation and the resulting technical results.

[0042] Step S1 uses copper raw materials as the processing object. Through batching detection, smelting and heat preservation treatment, the solid copper raw materials are transformed into copper liquid with controlled temperature and oxidation state.

[0043] In this step, the copper raw materials undergo batching and testing, smelting, and heat preservation treatment sequentially. Batching and testing confirm the purity and surface condition of the copper raw materials before they enter the furnace; smelting transforms the solid copper raw materials into flowable molten copper, controlling oxides and inclusions on the surface of the molten copper during the smelting process; heat preservation treatment maintains the temperature and surface coverage of the molten copper, and confirms the oxygen content of the molten copper. After batching and testing, smelting, and heat preservation treatment, a molten copper with controlled temperature and oxidation is formed.

[0044] When batching and inspecting copper raw materials before they enter the furnace, the inspection targets include the purity of the copper raw materials, the state of oil contamination on the surface of the copper raw materials, the state of water accumulation on the surface of the copper raw materials, and the state of obvious non-copper foreign matter in the copper raw materials. Copper raw materials are allowed to enter the smelting equipment as feed material when their surface is free of visible oil contamination, visible water accumulation, and obvious non-copper foreign matter. The mass fraction of copper in the copper raw materials should not be less than 99.95%; the surface condition of the copper raw materials should be free of visible oil contamination, visible water accumulation, and obvious non-copper foreign matter; the batching amount of copper raw materials should be controlled according to 60% to 95% of the rated capacity of the smelting equipment.

[0045] After the copper raw materials, having undergone batching and testing, are fed into the smelting equipment, they are heated and melted, gradually forming a flowing molten copper. During the smelting process, the surface of the molten copper is covered and isolated, and after the copper raw materials are completely melted, the slag and oxide film on the surface of the molten copper are skimmed off. The covering and isolation act on the surface of the molten copper, while the skimming process removes the slag and oxide film, reducing the ingress of external oxides and significant inclusions into the molten copper formed during the smelting stage. The smelting temperature is 1120℃ to 1200℃; the thickness of the covering layer during the smelting stage is 20mm to 80mm; the smelting time is based on the complete melting of the copper raw materials and the formation of a flowing molten copper; the skimming process is carried out after the copper raw materials are completely melted.

[0046] After the molten copper is placed in a holding state, the temperature and surface coverage of the copper are maintained, and the oxygen content of the copper is verified. During the holding process, the copper is kept within the set temperature range, the surface is kept covered, and the oxygen content test results are used to confirm the oxidation state of the copper. After the holding process, the copper is formed with controlled temperature and oxidation state. The holding temperature is 1100℃ to 1160℃; the holding time is 10 min to 60 min; the oxygen content control target of the copper before casting is 100 mg / kg to 400 mg / kg; the thickness of the covering layer during the holding stage is 20 mm to 80 mm.

[0047] Step S1 is achieved through smelting equipment, heat preservation equipment, temperature detection device, and oxygen content detection device. The smelting equipment receives the copper raw materials after the batching and testing are completed, and heats the copper raw materials to form molten copper; the heat preservation equipment receives the molten copper output from the smelting equipment and maintains the temperature of the molten copper and the state of the molten copper surface coverage.

[0048] Temperature detection devices monitor the temperature of the molten copper within the smelting and holding equipment, generating a temperature detection result. Oxygen content detection devices confirm the oxygen content of the molten copper before it exits the holding equipment, generating an oxygen content detection result. The temperature and oxygen content detection results are used to determine whether the molten copper is in a controlled temperature and oxidation state.

[0049] Step S2 takes the copper liquid with controlled temperature and oxidation as the processing object, and performs covering protection, smooth flow guidance and inclusion blocking treatment in the copper liquid transfer path to form a low oxygen and low inclusion copper liquid between the runner, ladle and nozzle.

[0050] In this step, such as Figure 2 The process involves sequentially covering and protecting the molten copper in its transfer path, stabilizing its flow, and blocking inclusions. Covering and protecting the molten copper surface at the runner, ladle, and nozzle reduces surface exposure. Stabilizing the flow controls the continuous flow of the molten copper in the runner and ladle. Blocking inclusions prevents scum, oxide film, and particles from entering the continuous casting zone, causing them to be blocked, floated, or retained before entering the zone. After these processes, the molten copper becomes low-oxygen, low-inclusion copper.

[0051] When introducing molten copper, with controlled temperature and oxidation states, into the copper transfer path from the insulation equipment, the copper surface is kept covered at the pouring tank, ladle, and nozzle. This covering protects the exposed copper surface, isolating it from the air and maintaining a controlled temperature during transfer. The copper transfer temperature is 1080℃ to 1150℃; the covering thickness during transfer is 20mm to 80mm; and the temperature drop along the copper transfer path does not exceed 40℃.

[0052] With the copper molten surface covered, the flow height and velocity of the copper molten in the runner and ladle are controlled to ensure a continuous and stable flow into the nozzle. During the stable flow guidance process, the turbulence of the copper molten surface is controlled, and the rupture of the oxide film on the copper molten surface and the entrainment of scum into the copper molten interior are limited. The copper molten flow velocity in the copper molten transfer path is 0.15 m / s to 0.80 m / s; the copper molten level fluctuation range in the runner is within ±10 mm; and the liquid flow state of the copper molten before entering the nozzle is continuous with no obvious interruption.

[0053] Based on the continuous and stable flow of molten copper in the runner and ladle, slag-blocking, settling, and filtration points are set in the copper transfer path. Slag-blocking points block the path of scum and oxide film entering the continuous casting zone with the molten copper; settling points allow density differences or changes in flow state to separate some inclusions from the main flow of molten copper; filtration points trap particulate inclusions. After inclusion blocking treatment, the molten copper, as a low-oxygen, low-inclusion copper liquid, arrives at the inlet of the continuous casting zone. The settling residence time is 10 to 60 seconds; the filter pore size is 10 to 40 ppi; the slag-blocking point is located before the gating nozzle inlet; the oxygen content control target before the low-oxygen, low-inclusion copper liquid enters the continuous casting zone is 100 mg / kg to 400 mg / kg.

[0054] Step S2 is achieved through a flow channel, ladle, nozzle, covering material, slag-blocking structure, settling structure, filtration structure, temperature detection device, and oxygen content detection device. The flow channel receives the molten copper output from the insulation equipment and transports it to the ladle or nozzle; the covering material is placed above the surface of the molten copper to maintain its coverage; the slag-blocking structure, settling structure, and filtration structure are installed in the molten copper transport path to block, float, or retain slag, oxide film, and particulate inclusions.

[0055] The temperature detection device measures the temperature of the molten copper at the inlet of the copper transfer path and the inlet of the continuous casting process, generating copper transfer temperature detection results and copper temperature drop detection results. The oxygen content detection device confirms the oxygen content of the molten copper at the continuous casting inlet, generating a copper oxygen content detection result for the continuous casting inlet. The copper transfer temperature detection results, copper temperature drop detection results, and copper oxygen content detection results at the continuous casting inlet are used to confirm whether a low-oxygen, low-inclusion copper solution has been formed.

[0056] Step S3 takes low-oxygen, low-inclusion copper liquid as the processing object, matches the continuous casting conditions according to the temperature state and inclusion control state of the low-oxygen, low-inclusion copper liquid, and solidifies the low-oxygen, low-inclusion copper liquid into shape through continuous casting.

[0057] In this step, such as Figure 3 The process involves continuous casting condition matching, copper molten metal pouring, crystallization cooling, and billet control, in sequence. Continuous casting condition matching determines the pouring temperature, casting speed, and crystallization cooling conditions based on the temperature, oxygen content, and flow characteristics of the low-oxygen, low-inclusion copper molten metal. Copper molten metal pouring allows the low-oxygen, low-inclusion copper molten metal to enter the crystallization zone of the continuous casting device and maintains a continuous supply within that zone. Crystallization cooling allows the low-oxygen, low-inclusion copper molten metal to gradually solidify into a hot-cast billet. Billet control ensures that the hot-cast billet is output from the continuous casting device at a set temperature and surface condition.

[0058] Based on the temperature, oxygen content control, and flow characteristics of the low-oxygen, low-inclusion copper melt, continuous casting conditions were set. These conditions included casting temperature, casting speed, crystallization cooling water temperature, and crystallization cooling water pressure. The casting temperature was set at 1080℃ to 1150℃; the casting speed at 6 m / min to 18 m / min; the crystallization cooling water temperature at 20℃ to 45℃; and the crystallization cooling water pressure at 0.15 MPa to 0.45 MPa. When the casting temperature was between 1120℃ and 1150℃, the casting speed was controlled at 6 m / min to 12 m / min; when the casting temperature was between 1080℃ and 1120℃, the casting speed was controlled at 10 m / min to 18 m / min.

[0059] After setting the continuous casting conditions, low-oxygen, low-inclusion copper liquid is introduced into the crystallization zone of the continuous casting apparatus, and the copper liquid level within the crystallization zone is controlled. The low-oxygen, low-inclusion copper liquid is continuously supplied within the crystallization zone, and the copper liquid level within the crystallization zone remains within a controlled fluctuation range. Under stable liquid level conditions, the copper liquid begins to solidify and forms a continuous solidification front. The copper liquid level fluctuation range in the crystallization zone is within ±8mm; the flow rate of copper liquid entering the crystallization zone matches the casting speed; and there must be no significant interruption in the flow of copper liquid within the crystallization zone.

[0060] After the liquid supply in the crystallization zone meets the requirements, the molten copper in the crystallization zone is cooled. During the crystallization cooling process, a continuous and uniform solidification shell forms on the surface of the molten copper, and the molten copper inside the solidification shell continues to solidify. The low-oxygen, low-inclusion molten copper gradually transforms from a liquid state into a hot-cast billet. The flow rate of the crystallization cooling water is adjusted synchronously with the casting speed; the flow rate of the crystallization cooling water is 20 m³ / h to 80 m³ / h.

[0061] After crystallization and cooling, the hot-cast billet is controlled to exit the continuous casting unit and enter the receiving area before continuous rolling. The exit temperature of the hot-cast billet is 850℃ to 980℃; the surface of the hot-cast billet must not have continuous cracks or obvious exposed slag inclusions. After the billet exit control, a hot-cast billet with a temperature suitable for continuous rolling is formed.

[0062] Step S3 is achieved through a continuous casting device, a crystallization cooling system, a temperature detection device, a liquid level detection device, and a controller. The continuous casting device receives low-oxygen, low-inclusion copper liquid and solidifies it in the crystallization zone to form a hot-cast billet; the crystallization cooling system cools the crystallization zone and operates according to the set crystallization cooling water temperature, crystallization cooling water pressure, and crystallization cooling water flow rate.

[0063] The temperature detection device monitors the casting temperature and the hot-cast billet exit temperature, generating casting temperature detection results and hot-cast billet exit temperature detection results, respectively. The liquid level detection device monitors the copper liquid level in the crystallization zone, generating copper liquid level detection results for the crystallization zone. Based on the casting temperature detection results, the hot-cast billet exit temperature detection results, and the copper liquid level detection results in the crystallization zone, the controller adjusts the molten copper supply from the gating nozzle, the casting speed, and the crystallization cooling water parameters to ensure that low-oxygen, low-inclusion copper liquid forms a hot-cast billet within the continuous casting device.

[0064] Step S4 takes the already formed hot-cast billet as the processing object, and through surface condition treatment and confirmation of the rolling temperature, makes the hot-cast billet into a suitable hot-cast billet for rolling.

[0065] In this step, such as Figure 3 The process involves sequentially performing surface condition treatment and roll entry temperature confirmation on the hot-cast billet. Surface condition treatment removes loose oxides, adhering particles, and surface contaminants from the billet surface, preventing or blocking surface substances that could be pressed into the copper rod surface during rolling. Roll entry temperature confirmation is performed on the hot-cast billet after surface condition treatment to determine whether it is in a suitable thermal state for plastic deformation. After surface condition treatment and roll entry temperature confirmation, the hot-cast billet is formed into a suitable-for-rolling hot-cast billet.

[0066] After the hot-cast billet is introduced into the receiving area before continuous rolling, its surface undergoes online cleaning. Online cleaning targets loose oxides, adhering particles, and surface contaminants on the billet surface. Methods include airflow cleaning or mechanical brushing. Airflow cleaning removes loose particles from the billet surface, while mechanical brushing removes loose oxides by brushing them, resulting in a surface free of continuously adhering loose oxide scale before rolling. The online cleaning location is between the outlet of the continuous casting unit and the inlet of the continuous rolling mill; the airflow cleaning pressure is 0.20 MPa to 0.60 MPa; the mechanical brushing speed is 500 r / min to 2000 r / min; and the surface of the hot-cast billet after online cleaning must be free of continuously adhering loose oxide scale.

[0067] The hot-cast billet that has undergone online cleaning is tested for its entry temperature, and its thermal state is confirmed based on the test results. When the entry temperature is between 750℃ and 950℃, the hot-cast billet that has undergone online cleaning is considered a suitable hot-cast billet for rolling. When the entry temperature is below 750℃, the conveying speed of the hot-cast billet into the continuous rolling mill is reduced, or the hot-cast billet is reheated. When the entry temperature is above 950℃, pre-rolling cooling is enhanced, or the residence time of the hot-cast billet in the pre-rolling receiving area is extended. The entry temperature should be between 750℃ and 950℃; the hot-cast billet conveying speed should be synchronized with the casting speed; the reheating temperature should not exceed 950℃; and the temperature of the hot-cast billet after pre-rolling cooling should not be lower than 750℃.

[0068] After the entry temperature is confirmed, hot-cast billets with a surface condition that meets the requirements and an entry temperature between 750°C and 950°C are considered suitable-for-rolling hot-cast billets. The confirmation criteria for suitable-for-rolling hot-cast billets include the surface condition of the hot-cast billet before entering the rolling mill and the temperature condition of the hot-cast billet before entering the continuous rolling mill.

[0069] Step S4 is achieved through the pre-rolling receiving area, online cleaning device, temperature detection device, and conveying device. The pre-rolling receiving area is located between the continuous casting unit and the continuous rolling mill, and is used to receive hot-cast billets and to perform surface treatment and confirmation of the entry temperature.

[0070] An online cleaning device performs airflow cleaning or mechanical brushing on the surface of the hot-cast billet, resulting in a surface condition treatment. A temperature detection device monitors the entry temperature of the hot-cast billet into the rolling mill, generating an entry temperature detection result. A conveying device transports suitable hot-cast billets whose surface condition and entry temperature meet the requirements.

[0071] Step S5 takes the already formed suitable hot-cast billet as the processing object, and transforms the suitable hot-cast billet into a low-oxygen, high-conductivity copper rod through continuous rolling, post-rolling cooling and cleaning, drying and protection, and coiling.

[0072] In this step, continuous rolling, cooling and lubricating medium supply, post-rolling cooling and cleaning, drying and protection, and coiling are performed sequentially. Continuous rolling is used to gradually deform the suitable hot-cast billet into a copper rod of the target specification through continuous rolling passes; cooling and lubricating medium supply is used to keep the rolling deformation area under continuous cooling and lubrication; post-rolling cooling and cleaning is used to remove oxides, copper powder, and cooling and lubricating residues from the surface of the rolled copper rod; drying and protection is used to remove residual liquids from the surface of the copper rod and form a protective layer on the surface of the copper rod; coiling is used to form a low-oxygen, high-conductivity copper rod finished product after drying and protection.

[0073] After the suitable hot-cast billet is fed into the continuous rolling mill, it is rolled in a continuous pass reduction manner. During the rolling process, the continuous rolling mill operates at a set rolling speed, and each rolling pass continuously deforms the suitable hot-cast billet according to a set reduction rate, so that the cross-section of the suitable hot-cast billet is gradually reduced to form a copper rod of the target specification. The continuous rolling inlet temperature is 750℃ to 950℃; the single-pass reduction rate is 10% to 35%; the total reduction rate is determined according to the target copper rod diameter; the rolling speed is 5m / s to 25m / s; and the target copper rod diameter is 8.0mm ± 0.3mm.

[0074] During continuous rolling, a cooling and lubricating medium is supplied to the rolling deformation zone. This medium acts on the rolls, the hot-cast billet, and the deforming copper rod, ensuring a continuous supply of cooling and lubricating medium to the rolling deformation zone and reducing surface adhesion. The temperature of the cooling and lubricating medium is 20°C to 45°C; the emulsion concentration is 1.0% to 4.0%; the pressure is 0.20 MPa to 0.60 MPa; and the supply rate of the cooling and lubricating medium is adjusted synchronously with the rolling speed.

[0075] The rolled copper rod undergoes post-rolling cooling and cleaning. Post-rolling cooling addresses the thermal state of the rolled copper rod, while post-rolling cleaning removes oxides, copper powder, and cooling / lubricating residues from the rod surface. This process removes surface contaminants and ensures the copper rod reaches a set surface temperature before entering the drying and protective treatment stage. The post-rolling cooling water temperature is 20°C to 45°C; the post-rolling cleaning pressure is 0.20 MPa to 0.80 MPa; the surface temperature of the cooled copper rod is 40°C to 90°C; and the cleaning medium is water or a suitable cleaning solution for the copper rod surface.

[0076] The cooled and cleaned copper rod is dried, and a protective coating is applied to its surface. The drying process removes any residual liquid from the copper rod surface, ensuring no continuous water film remains. The protective coating is applied to the surface of the copper rod, creating a protective agent coating. The drying air pressure is 0.20 MPa to 0.60 MPa; no continuous water film should remain on the surface of the copper rod after drying; the amount of protective agent applied is 0.02 g / m² to 0.10 g / m².

[0077] The dried and protected copper rod is wound up to form a low-oxygen, high-conductivity copper rod. The winding tension is 50N to 300N; the oxygen content of the finished copper rod is controlled to be 100mg / kg to 400mg / kg; the volume resistivity of the finished copper rod at 20℃ is not greater than 0.017241Ω·mm² / m.

[0078] Step S5 is achieved through a continuous rolling mill, a cooling and lubrication supply device, a post-rolling cooling and cleaning device, a drying device, a surface protection device, and a coiling device. The continuous rolling mill receives the suitable hot-cast billet and outputs the copper rod of the target specification in a continuous pass rolling manner; the cooling and lubrication supply device supplies cooling and lubrication medium to the rolling deformation zone and keeps the rolling deformation zone in a state of cooling and lubrication medium supply.

[0079] The post-rolling cooling and cleaning unit cools and cleans the rolled copper rod, forming a cooled and cleaned copper rod. The drying unit dries the surface of the cooled and cleaned copper rod, forming a copper rod without a continuous water film on its surface. The surface protection unit applies a protective agent coating to the surface of the copper rod. The winding unit winds the copper rod after surface protection treatment, forming a low-oxygen, high-conductivity copper rod.

[0080] The copper raw materials, filters, cooling and lubricating media, and surface protectants used in the following examples and comparative examples can be commercially available materials.

[0081] The copper raw materials can be cathode copper, electrolytic copper or No. 1 standard copper that conforms to GB / T 467 or equivalent standards. When conducting the reproduction experiment, the copper raw materials with a copper mass fraction of not less than 99.95%, from the same batch, with no visible oil stains, no visible water accumulation, and no obvious non-copper foreign matter on the surface should be used.

[0082] The filter element can be a ceramic foam filter element for molten metal filtration or an equivalent high-temperature resistant molten metal filter element. The pore size can be selected as 10ppi, 30ppi, 40ppi or 50ppi according to the examples and comparative examples. The supply source can refer to SELEE ceramic foam filter for copper, Foseco / Vesuvius SEDEX silicon carbide ceramic foam filter for copper-based alloys or other similar products that can provide the same pore size, withstand the temperature of copper liquid of about 1120°C and are suitable for copper or copper-based alloy molten metal filtration.

[0083] The cooling and lubricating medium can be a water-diluted cooling and lubricating fluid for hot rolling of copper rods, such as Quaker Houghton's QH EVEROLL C series, COPPERSHIELD series, or equivalent copper rod hot rolling cooling and lubricating products. When using, prepare an emulsion with a mass concentration of 2.5% according to the example and control the temperature of the cooling and lubricating medium at 30°C. The 2.5% mass concentration cooling and lubricating emulsion can be prepared as follows: Weigh 25.0g of the copper rod hot rolling water-diluted cooling and lubricating medium stock solution based on the amount of 1000.0g of cooling and lubricating emulsion, add it to 975.0g of water, and stir at 300r / min for 10min at 25°C to uniformly disperse the cooling and lubricating medium, obtaining a 2.5% mass concentration cooling and lubricating emulsion. Before use, circulate and mix the obtained cooling and lubricating emulsion for 5min, and control the operating temperature to 30°C through heat exchange or constant temperature methods, then supply it to the continuous rolling deformation zone. If the formulation is to be scaled up for production, it should be scaled up proportionally according to the mass ratio of 25.0:975.0, without changing the 2.5% mass concentration.

[0084] Surface protective agents can be copper surface anti-tarnishing agents, copper antioxidants, or copper surface protectants, such as copper anti-tarnishing agents, heat-resistant copper anti-tarnishing agents, copper antioxidants, or equivalent copper surface protection products from JXMetals Trading / JX Advanced Metals. When using them, the standard is that they can form a protective layer on the copper rod surface, do not significantly affect the conductivity of the copper rod, and meet the coating amount of 0.05g / m.

[0085] All of the above materials are publicly available or subject to price inquiry. Specific suppliers and specifications can be replaced within the range of equivalent purity, pore size, application temperature, cooling and lubrication performance, or surface protection level, depending on the experimental reproduction needs. This does not constitute a limitation on a particular supplier or model.

[0086] Example 1:

[0087] This embodiment provides a continuous casting and rolling method for producing low-oxygen, high-conductivity copper rods. In this embodiment, the workshop temperature is 25°C, the relative humidity is 50%, the copper raw materials are from the same batch, and the target diameter of the finished copper rod is 8.0 mm. The method includes the following steps:

[0088] S1: The copper raw materials are batched, tested, smelted, and heat-preserved to form a copper liquid with controlled temperature and oxidation state.

[0089] The copper raw materials undergo batching and pre-furnace testing. The copper content in the raw materials is 99.95% by mass, and the surface of the raw materials is free of visible oil, water, and obvious non-copper foreign matter. The batch size of copper raw materials is controlled at 80% of the rated capacity of the smelting equipment. The tested copper raw materials are then fed into the smelting equipment and smelted at 1160℃. During the smelting stage, the thickness of the copper liquid surface coating is 50mm. After the copper raw materials are completely melted and form a flowable copper liquid, the slag and oxide film on the surface of the copper liquid are skimmed off.

[0090] The molten copper is transferred to a heat-holding device and held at 1130℃ for 30 minutes, with a copper surface coating thickness of 50mm during the heat-holding stage. The oxygen content of the molten copper is monitored during the heat-holding process, with a target oxygen content of 250mg / kg before entering the copper transfer path. After batching, smelting, and heat-holding, a copper liquid with controlled temperature and oxidation states is formed.

[0091] S2: Covering protection, smooth flow guidance and inclusion blocking treatment are carried out in the copper liquid transfer path to form a low-oxygen and low-inclusion copper liquid.

[0092] The molten copper formed in S1 is introduced from the heat preservation equipment into the molten copper transfer path. The molten copper transfer temperature is 1120℃, and the temperature drop of the molten copper between the outlet of the heat preservation equipment and the inlet of the continuous casting is 20℃. The molten copper surface is kept covered at the runner, ladle, and nozzle, and the thickness of the covering layer during the transfer stage is 20mm.

[0093] With the copper liquid surface covered, the flow state of the copper liquid in the runner and ladle is controlled. The copper liquid flow velocity in the copper liquid transfer path is 0.80 m / s, the maximum fluctuation of the copper liquid surface in the runner is 8 mm, and the copper liquid maintains continuous flow without obvious interruption before entering the nozzle.

[0094] Slag-blocking, settling, and filtration points are set up along the copper molten material transfer path. The settling residence time is 10 seconds, the filter element pore size is 10 ppi, and the slag-blocking point is located before the gating nozzle inlet. The oxygen content of the copper molten material at the continuous casting inlet is controlled to 250 mg / kg. After covering protection, smooth flow guidance, and inclusion blocking treatment, a low-oxygen, low-inclusion copper molten material is formed.

[0095] S3: Based on the temperature state and inclusion control state of the low-oxygen, low-inclusion copper liquid, match the continuous casting conditions and carry out continuous casting to form a hot-cast billet with a temperature suitable for continuous rolling.

[0096] Based on the temperature, oxygen content control, and flow characteristics of the low-oxygen, low-inclusion copper melt formed by S2, continuous casting conditions were set. The casting temperature was 1120℃, the casting speed was 12m / min, the crystallization cooling water temperature was 30℃, the crystallization cooling water pressure was 0.30MPa, and the crystallization cooling water flow rate was 50m³ / h.

[0097] Low-oxygen, low-inclusion copper molten metal is introduced into the crystallization zone of the continuous casting unit. The maximum fluctuation of the copper molten metal surface in the crystallization zone is 4 mm. The molten metal supply from the gating nozzle is matched with the continuous casting output, and the copper molten metal supply in the crystallization zone is continuous with no significant interruption. The low-oxygen, low-inclusion copper molten metal solidifies in the crystallization zone to form a hot-cast billet. The hot-cast billet exits at a temperature of 910℃, and the surface of the hot-cast billet shows no continuous cracking or obvious slag exposure. After continuous casting, a hot-cast billet with a temperature suitable for continuous rolling is formed.

[0098] S4: Perform surface condition treatment and confirm the rolling temperature for the hot-cast billet to form a suitable hot-cast billet.

[0099] The hot-cast billet formed in S3 is introduced into the receiving area before continuous rolling, and its surface is cleaned online between the outlet of the continuous casting unit and the inlet of the continuous rolling mill. Online cleaning is performed using an airflow cleaning method at a pressure of 0.40 MPa. The targets of online cleaning are loose particles, loose oxides, and surface contaminants on the surface of the hot-cast billet. After online cleaning, the surface of the hot-cast billet is free of continuously adhering loose oxide scale.

[0100] The hot-cast billet, after online cleaning, undergoes inlet temperature testing. The inlet temperature of the hot-cast billet before entering the continuous rolling mill is 850℃. The hot-cast billet conveying speed is synchronized with the casting speed. After surface treatment and inlet temperature confirmation, a suitable-for-rolling hot-cast billet is formed.

[0101] S5: Utilizing suitable hot-cast billets for continuous rolling, followed by cooling, cleaning, drying, protection, and coiling, a low-oxygen, high-conductivity copper rod is formed.

[0102] The hot-rolled billet formed by S4 is fed into a continuous rolling mill with an inlet temperature of 850℃. The continuous rolling mill performs rolling in a continuous pass reduction manner, with a single pass reduction rate of 20%. The total reduction rate is determined by forming a target copper rod with a diameter of 8.0mm, and the rolling speed is 15m / s.

[0103] During continuous rolling, a cooling and lubricating medium is supplied to the rolling deformation zone. The temperature of the cooling and lubricating medium is 30℃, the emulsion mass concentration is 2.5%, the pressure of the cooling and lubricating medium is 0.40MPa, and the supply rate of the cooling and lubricating medium is set synchronously according to the rolling speed of 15m / s.

[0104] The rolled copper rod is subjected to post-rolling cooling and cleaning. The post-rolling cooling water temperature is 30℃, the post-rolling cleaning pressure is 0.50MPa, the surface temperature of the cooled copper rod is 60℃, and the post-rolling cleaning medium is water.

[0105] The cooled and cleaned copper rods undergo drying and surface protection treatment. The drying air pressure is 0.40 MPa, and after drying, there is no continuous water film on the surface of the copper rod. The surface protective agent coating amount is 0.05 g / m. The dried and protected copper rods are then wound up at a tension of 150 N to form low-oxygen, high-conductivity copper rods.

[0106] Example 2:

[0107] In this embodiment, the difference from Embodiment 1 is that in S2, the thickness of the covering layer during the transfer stage is 50 mm, the flow rate of the copper liquid in the copper liquid transfer path is 0.40 m / s, the settling residence time is 35 s, and the pore size of the filter element is 30 ppi. The remaining steps are the same as in Embodiment 1.

[0108] Example 3:

[0109] In this embodiment, the difference from Embodiment 1 is that in S2, the thickness of the covering layer during the transfer stage is 80 mm, the flow rate of the copper liquid in the copper liquid transfer path is 0.15 m / s, the settling residence time is 60 s, and the pore size of the filter element is 40 ppi. The remaining steps are the same as in Embodiment 1.

[0110] Example 4:

[0111] In this embodiment, the differences from Embodiment 2 are as follows: In S3, the casting temperature is 1080℃, the casting speed is 18m / min, the crystallization cooling water pressure is 0.45MPa, and the hot-cast billet exit temperature is 850℃; in S4, the hot-cast billet inlet temperature before entering the continuous rolling mill is 750℃; in S5, the continuous rolling inlet temperature is 750℃. The remaining steps are the same as in Embodiment 2.

[0112] Example 5:

[0113] In this embodiment, the difference from Embodiment 2 is as follows: In S3, the casting temperature is 1150℃, the casting speed is 6m / min, the crystallization cooling water pressure is 0.20MPa, and the hot-cast billet exit temperature is 980℃; in S4, the hot-cast billet entry temperature before entering the continuous rolling mill is 950℃; in S5, the continuous rolling entry temperature is 950℃. The remaining steps are the same as in Embodiment 2.

[0114] Comparative Example 1:

[0115] In this comparative example, the difference from Example 1 is that in S2, the thickness of the covering layer during the transfer stage is 5 mm, the flow rate of the copper liquid in the copper liquid transfer path is 1.00 m / s, the settling residence time is 5 s, and no filter is installed in the copper liquid transfer path. The remaining steps are the same as in Example 1.

[0116] Comparative Example 2:

[0117] In this comparative example, the differences from Example 2 are as follows: In S3, the casting temperature is 1060℃, the casting speed is 20m / min, the crystallization cooling water pressure is 0.30MPa, and the hot-cast billet exit temperature is 800℃; In S4, the hot-cast billet's entry temperature before entering the continuous rolling mill is 720℃, and no additional heating to 750℃ is performed on the hot-cast billet; In S5, the continuous rolling mill entry temperature is 720℃. The remaining steps are the same as in Example 2.

[0118] Comparative Example 3:

[0119] In this comparative example, the difference from Example 2 is that in S2, the thickness of the covering layer during the transfer stage is 100 mm, the flow rate of the copper liquid in the copper liquid transfer path is 0.10 m / s, the settling residence time is 90 s, and the pore size of the filter element is 50 ppi. The remaining steps are the same as in Example 2.

[0120] Comparative Example 4:

[0121] In this comparative example, the differences from Example 2 are as follows: In S3, the casting temperature is 1170℃, the casting speed is 5m / min, the crystallization cooling water pressure is 0.30MPa, and the hot-cast billet exit temperature is 1000℃; In S4, the hot-cast billet's entry temperature before entering the continuous rolling mill is 970℃, and the hot-cast billet temperature is not reduced to 950℃ by pre-rolling cooling; In S5, the continuous rolling mill entry temperature is 970℃. The remaining steps are the same as in Example 2.

[0122] Comparative Example 5:

[0123] This comparative example provides a conventional method for preparing low-oxygen copper rods through continuous casting and rolling. In this comparative example, the workshop temperature is 25°C, the relative humidity is 50%, the copper raw material is from the same batch as in Example 1, and the target diameter of the finished copper rod is 8.0 mm. The method includes the following steps:

[0124] M1: The copper raw materials are subjected to batching, testing, smelting, and heat preservation treatment.

[0125] Copper raw materials undergo batching and pre-furnace testing. The copper content in the raw materials is 99.95% by mass, and the surface is free of visible oil, water, and obvious non-copper foreign matter. The batch size of copper raw materials is controlled at 80% of the rated capacity of the smelting equipment. The tested copper raw materials are then fed into the smelting equipment and smelted at 1160℃, with a copper molten metal surface layer thickness of 50mm during the smelting stage. After the copper raw materials are completely melted and form a flowable copper molten metal, the slag and oxide film on the surface of the copper molten metal are removed. The smelted copper molten metal is then transferred to a holding device and held at 1130℃ for 30 minutes, with a copper molten metal surface layer thickness of 50mm during the holding stage. The oxygen content of the copper molten metal before transfer is controlled to be 250mg / kg.

[0126] M2: Transferring the molten copper after heat preservation.

[0127] The molten copper formed in M1 is transported to the nozzle through a runner and ladle. The copper transfer temperature is 1120℃, and the coating thickness during the transfer stage is 20mm. The flow velocity of the molten copper in the runner and ladle is 0.80m / s. In this step, the settling residence time and filter pore size are not set according to the low-oxygen, low-inclusion control intensity requirements during copper transfer, and no filter is installed in the copper transfer path.

[0128] M3: Continuous casting of molten copper after transfer.

[0129] The molten copper transferred from M2 is introduced into the crystallization zone of the continuous casting apparatus, and continuous casting is carried out according to fixed casting temperature, fixed casting speed, and cooling conditions. The casting temperature is 1120℃, the casting speed is 12m / min, the crystallization cooling water temperature is 30℃, the crystallization cooling water pressure is 0.30MPa, the crystallization cooling water flow rate is 50m³ / h, and the hot-cast billet exit temperature is 910℃. After continuous casting, a hot-cast billet is formed.

[0130] M4: Feed the hot-cast billet into the continuous rolling mill.

[0131] The hot-cast billet formed in M3 is conveyed from the outlet of the continuous casting unit to the inlet of the continuous rolling mill. The temperature of the hot-cast billet before entering the continuous rolling mill is 850℃. This step does not involve any connection control linked to the surface condition and entry temperature of the hot-cast billet, and does not include online cleaning treatment for loose oxides, floating particles, and surface contaminants on the surface of the hot-cast billet.

[0132] M5: Continuous rolling, cooling, cleaning, and coiling of hot-cast billets.

[0133] The hot-cast billet from M4 is fed into the continuous rolling mill, with an inlet temperature of 850℃. The continuous rolling mill operates on a continuous-pass reduction method, with a single-pass reduction rate of 20%. The total reduction rate is determined by forming a target copper rod with a diameter of 8.0mm, and the rolling speed is 15m / s.

[0134] During continuous rolling, a cooling and lubricating medium is supplied to the rolling deformation zone. The temperature of the cooling and lubricating medium is 30℃, the emulsion concentration is 2.5%, and the pressure is 0.40 MPa. The rolled copper rod is then cooled and cleaned. The post-rolling cooling water temperature is 30℃, the post-rolling cleaning pressure is 0.50 MPa, and the surface temperature of the cooled copper rod is 60℃. The post-rolling cleaning medium is water. After cooling and cleaning, the copper rod undergoes drying and surface protection treatment. The drying air pressure is 0.40 MPa, and the surface protective agent coating amount is 0.05 g / m. The dried and protected copper rod is then wound up at a tension of 150 N to form a low-oxygen copper rod.

[0135] Experimental Example 1:

[0136] The experimental subjects in this example are the molten copper, hot-cast billet, and finished copper rod in the preparation process of Examples 1 to 5 and Comparative Examples 1 to 5.

[0137] The following tests were conducted on the experimental subjects. All experiments used the same batch of copper raw materials, with a copper mass fraction of 99.95%. The surface of the copper raw materials was free of visible oil, water, and obvious non-copper foreign matter. The smelting equipment, heat preservation equipment, continuous casting device, continuous rolling mill, cooling and cleaning device, drying device, and coiling device were kept consistent across all experiments. Samples were taken after 30 minutes of continuous and stable production in each group. Three replicate batches were conducted for each group. For each replicate batch, samples of molten copper, hot-cast billets, and finished copper rods were taken, with each replicate batch containing at least 100 meters of finished copper rods. The workshop temperature was 25℃, and the relative humidity was 50%.

[0138] Test 1: Oxygen Content Test of Finished Copper Rods. Samples were taken from the finished copper rods prepared in Examples 1 to 5 and Comparative Examples 1 to 5. The oxygen content of the finished copper rods was measured using an oxygen content analyzer. The test output is the oxygen content of the finished copper rod, in mg / kg. The oxygen content of the finished copper rods is used to evaluate the retention of low oxygen state in molten copper during copper transfer, continuous casting, continuous rolling, and post-processing.

[0139] Test 2: Ingot Internal Defect Area Ratio Test. Samples were taken from the cross-sections of the hot-cast ingots prepared in Examples 1 to 5 and Comparative Examples 1 to 5. After metallographic sample preparation and cross-sectional image acquisition, the proportion of the defect area to the total area of ​​the observed cross-section was statistically analyzed. The test output is the ingot internal defect area ratio, expressed as a percentage. The ingot internal defect area ratio is calculated using the following formula:

[0140] The internal defect area ratio of the billet = area of ​​the defect region / total area of ​​the observation section × 100%.

[0141] The unit for the defect area is mm², the unit for the total area of ​​the observed cross section is mm², and the unit for the calculated output is %. The internal defect area ratio of the billet is used to evaluate the formation of porosity, inclusions, shrinkage cavities, and cracks during the continuous casting stage.

[0142] Test 3: Volume resistivity test of finished copper rods at 20°C. Samples were cut from the finished copper rods prepared in Examples 1 to 5 and Comparative Examples 1 to 5, and volume resistivity tests were performed at 20°C using a resistivity testing device. The test output is the volume resistivity of the finished copper rod at 20°C, in Ω·mm² / m. The volume resistivity of the finished copper rod at 20°C is used to evaluate the conductivity of the finished copper rod.

[0143] Test 4: Surface Defect Count Test of Finished Copper Rods. Surface inspection was performed on each 100m continuous finished copper rod from Examples 1 to 5 and Comparative Examples 1 to 5. The number of visible indentations, continuous oxide scale residue, obvious copper powder adhesion, and linear surface defects was counted. The test output was the surface defect count of the finished copper rod, in units of defects / 100m. The surface defect count of the finished copper rod was used to evaluate the impact of hot-cast billet surface treatment, continuous rolling cooling and lubrication, and post-rolling cooling and cleaning on the surface condition of the finished copper rod.

[0144] The test results are shown in Table 1:

[0145] Table 1

[0146] Example 1 246 0.32 0.01725 5.8 Example 2 168 0.18 0.01716 3.6 Example 3 182 0.29 0.01722 5.0 Example 4 174 0.50 0.01731 7.4 Example 5 176 0.42 0.01727 6.6 Comparative Example 1 382 0.95 0.01745 14.2 Comparative Example 2 238 1.10 0.01750 17.0 Comparative Example 3 214 0.88 0.01741 13.4 Comparative Example 4 252 0.92 0.01744 15.1 Comparative Example 5 306 0.47 0.01732 8.7

[0147] Examples 1, 2, and 3 were used to evaluate the effect of low-oxygen, low-inclusion control intensity on test indicators during copper liquid transfer. In Example 1, the coating thickness during the transfer stage was 20 mm, the copper liquid flow rate was 0.80 m / s, the settling residence time was 10 s, and the filter element pore size was 10 ppi. In Example 2, the coating thickness during the transfer stage was 50 mm, the copper liquid flow rate was 0.40 m / s, the settling residence time was 35 s, and the filter element pore size was 30 ppi. Under the conditions of maintaining the hot-condition matching strength of casting-continuous rolling at a casting temperature of 1120℃, a casting speed of 12m / min, a crystallization cooling water pressure of 0.30MPa, a hot-cast billet exit temperature of 910℃, and a rolling temperature of 850℃, the finished copper rod of Example 1 had an oxygen content of 246mg / kg, an internal defect area ratio of 0.32%, a volume resistivity of 0.01725Ω·mm² / m at 20℃, and 5.8 surface defects per 100m; the finished copper rod of Example 2 had an oxygen content of 168mg / kg, an internal defect area ratio of 0.18%, a volume resistivity of 0.01716Ω·mm² / m at 20℃, and 3.6 surface defects per 100m.

[0148] The above results show that after adjusting the thickness of the covering layer from 20 mm to 50 mm, the copper liquid flow velocity from 0.80 m / s to 0.40 m / s, the settling residence time from 10 s to 35 s, and the filter element pore size from 10 ppi to 30 ppi, the liquid surface coverage, flow stability, and inclusion retention of the copper liquid in the runner, ladle, and nozzle are all constrained. The oxygen content of the finished copper rod, the internal defect area ratio of the billet, the volume resistivity of the finished copper rod at 20℃, and the number of surface defects of the finished copper rod are all reduced.

[0149] In Example 3, the coating thickness during the transfer stage was 80 mm, the copper melt flow rate was 0.15 m / s, the settling residence time was 60 s, and the filter pore size was 40 ppi. Under the conditions of maintaining the casting-continuous rolling hot-state matching strength at a casting temperature of 1120℃, a casting speed of 12 m / min, a crystallization cooling water pressure of 0.30 MPa, a hot-cast billet exit temperature of 910℃, and a rolling temperature of 850℃, the finished copper rod of Example 3 had an oxygen content of 182 mg / kg, an internal defect area ratio of 0.29%, a volume resistivity of 0.01722 Ω·mm² / m at 20℃, and 5.0 surface defects per 100 m. Compared to Example 2, all four test indicators of Example 3 were increased. This is because when the coating thickness reaches 80mm, the copper liquid flow rate drops to 0.15m / s, the settling residence time is extended to 60s, and the filter element pore size reaches 40ppi, the copper liquid transfer resistance and the risk of transfer temperature drop increase, the thermal state of the copper liquid entering the crystallization zone fluctuates, and the defect state of the billet and the surface state of the finished copper rod change accordingly.

[0150] Examples 2, 4, and 5 were used to evaluate the effect of casting-continuous rolling hot condition matching strength on test indicators. In Example 2, the casting temperature was 1120℃, the casting speed was 12m / min, the crystallization cooling water pressure was 0.30MPa, the hot-cast billet exit temperature was 910℃, and the rolling temperature was 850℃. In Example 4, the casting temperature was 1080℃, the casting speed was 18m / min, the crystallization cooling water pressure was 0.45MPa, the hot-cast billet exit temperature was 850℃, and the rolling temperature was 750℃. Under the conditions of maintaining low oxygen and low inclusion control intensity during copper molten transfer (with a coating thickness of 50 mm, copper molten flow rate of 0.40 m / s, settling residence time of 35 s, and filter pore size of 30 ppi), the finished copper rod of Example 4 had an oxygen content of 174 mg / kg, an internal defect area ratio of 0.50%, a volume resistivity of 0.01731 Ω·mm² / m at 20°C, and 7.4 surface defects per 100 m. Compared with Example 2, the oxygen content of the finished copper rod in Example 4 was similar, but the internal defect area ratio of the cast billet, the volume resistivity of the finished copper rod at 20°C, and the number of surface defects increased. This is because when the casting temperature drops to 1080℃, the casting speed increases to 18m / min, the crystallization cooling water pressure increases to 0.45MPa, the hot billet exit temperature drops to 850℃ and the rolling temperature drops to 750℃, a low-temperature mismatch occurs in the solidification process and the rolling hot state, and the defect area ratio inside the billet and the number of defects on the surface of the finished copper rod increase accordingly.

[0151] In Example 5, the casting temperature was 1150℃, the casting speed was 6m / min, the crystallization cooling water pressure was 0.20MPa, the hot-cast billet exit temperature was 980℃, and the rolling temperature was 950℃. Under the conditions of maintaining low oxygen and low inclusion control strength during copper liquid transfer (with a coating thickness of 50mm, copper liquid flow rate of 0.40m / s, settling residence time of 35s, and filter pore size of 30ppi), the finished copper rod of Example 5 had an oxygen content of 176mg / kg, an internal defect area ratio of 0.42%, a volume resistivity of 0.01727Ω·mm² / m at 20℃, and 6.6 surface defects per 100m. Compared with Example 2, Example 5 showed an increase in the internal defect area ratio of the billet, the volume resistivity of the finished copper rod at 20℃, and the number of surface defects. This is because when the casting temperature rises to 1150℃, the casting speed drops to 6m / min, the crystallization cooling water pressure drops to 0.20MPa, the hot casting billet exit temperature rises to 980℃ and the rolling temperature rises to 950℃, the risk of oxide formation on the hot casting billet surface and adhesion on the rolling surface increases, and the surface condition and conductivity of the finished copper rod change.

[0152] Example 2 simultaneously employed the following parameters: a coating thickness of 50 mm during the transfer stage, a copper melt flow rate of 0.40 m / s, a settling residence time of 35 s, a filter pore size of 30 ppi, a casting temperature of 1120℃, a casting speed of 12 m / min, a crystallization cooling water pressure of 0.30 MPa, a hot-cast billet exit temperature of 910℃, and a rolling temperature of 850℃. The finished copper rod from Example 2 had an oxygen content of 168 mg / kg, an internal defect area ratio of 0.18%, a volume resistivity of 0.01716 Ω·mm² / m at 20℃, and 3.6 surface defects per 100 m. All four test indicators for Example 2 fell within the lower range of the example group, indicating a synergistic relationship between the low-oxygen, low-inclusion control strength during copper melt transfer and the matching strength of the casting-continuous rolling hot state.

[0153] From the perspective of state changes, during the transfer stage, the coating thickness of 50mm, the copper liquid flow rate of 0.40m / s, the settling residence time of 35s, and the filter pore size of 30ppi ensure that the copper liquid maintains a covered and protected state, stable flow guidance, and inclusion blocking state between the runner, ladle, and nozzle. This restricts the rupture of the copper liquid oxide film, the entrapment of scum, and the entry of particulate inclusions. The casting temperature of 1120℃, casting speed of 12m / min, crystallization cooling water pressure of 0.30MPa, hot-cast billet exit temperature of 910℃, and rolling temperature of 850℃ ensure that the low-oxygen, low-inclusion copper liquid forms a hot-cast billet according to matched casting, solidification, and exit conditions during the continuous casting stage, and that the hot-cast billet enters the rolling state at a matched rolling temperature. The copper liquid transfer state is interconnected with the solidification and rolling hot state, ensuring that the oxygen content of the finished copper rod, the internal defect area ratio of the billet, the volume resistivity of the finished copper rod at 20℃, and the number of surface defects in the finished copper rod are all kept within a low range.

[0154] Both Examples 1 and 3 used a casting temperature of 1120℃, a casting speed of 12m / min, a crystallization cooling water pressure of 0.30MPa, a hot-cast billet exit temperature of 910℃, and a rolling temperature of 850℃. However, the parameters corresponding to the low-oxygen, low-inclusion control intensity during copper liquid transfer differed. In Example 1, the coating thickness during the transfer stage was 20mm, the copper liquid flow rate was 0.80m / s, the settling residence time was 10s, and the filter pore size was 10ppi. In Example 3, the coating thickness during the transfer stage was 80mm, the copper liquid flow rate was 0.15m / s, the settling residence time was 60s, and the filter pore size was 40ppi. The oxygen content, internal defect area ratio of the billet, and number of surface defects in the finished copper rods of Examples 1 and 3 were all higher than those of Example 2. This is because simply maintaining the matching conditions of the casting-continuous rolling thermal state cannot eliminate the changes in the copper liquid oxidation state and inclusion entry state caused by the deviation of the low-oxygen, low-inclusion control intensity parameters during copper liquid transfer from the parameter combination of Example 2.

[0155] Both Examples 4 and 5 used a 50mm thick coating layer during the transfer stage, a copper melt flow rate of 0.40m / s, a settling time of 35s, and a filter pore size of 30ppi. However, the parameters corresponding to the matching strength of the casting-continuous rolling hot state differed. In Example 4, the casting temperature was 1080℃, the casting speed was 18m / min, the crystallization cooling water pressure was 0.45MPa, the hot-cast billet exit temperature was 850℃, and the rolling temperature was 750℃. In Example 5, the casting temperature was 1150℃, the casting speed was 6m / min, the crystallization cooling water pressure was 0.20MPa, the hot-cast billet exit temperature was 980℃, and the rolling temperature was 950℃. The oxygen content of the finished copper rods in Examples 4 and 5 was 174mg / kg and 176mg / kg, respectively, which was close to that of Example 2. However, the internal defect area ratio of the billet, the volume resistivity of the finished copper rod at 20℃, and the number of surface defects of the finished copper rod were all higher than those in Example 2. This is because forming a relatively stable low-oxygen, low-inclusion copper liquid cannot replace the matching control between continuous casting conditions and the hot state of the rolling mill; when the matching strength parameters of the casting-continuous rolling hot state deviate from the parameter combination of Example 2, the low-oxygen, low-inclusion copper liquid may still form defect states and surface state fluctuations during solidification and rolling.

[0156] Comparative Example 5 illustrates an existing low-oxygen copper rod continuous casting and rolling preparation method. The finished copper rod has an oxygen content of 306 mg / kg, an internal defect area ratio of 0.47%, a volume resistivity of 0.01732 Ω·mm² / m at 20℃, and 8.7 surface defects per 100m. Comparative Example 5 employs conventional transfer, fixed casting temperature, fixed casting speed, conventional cooling conditions, and conventional cooling, cleaning, and coiling methods. It does not utilize the low-oxygen, low-inclusion control strength parameter combination for copper liquid transfer and the matching strength parameter combination for casting-continuous rolling thermal states as described in Example 2 for continuous bearing control. Compared to Example 2, all four test indicators for Comparative Example 5 are in the higher range, indicating that the continuous coordination between the copper liquid transfer state, continuous casting state, and continuous rolling bearing state in Example 2 corresponds to the changes in the test indicators.

[0157] In Comparative Example 1, the thickness of the coating layer during the transfer stage was 5 mm, lower than the range of 20 mm to 80 mm in the method embodiment; the copper liquid flow rate was 1.00 m / s, higher than the range of 0.15 m / s to 0.80 m / s in the method embodiment; the settling residence time was 5 s, lower than the range of 10 s to 60 s in the method embodiment; and no filter was installed. The finished copper rod of Comparative Example 1 had an oxygen content of 382 mg / kg, an internal defect area ratio of 0.95%, a volume resistivity of 0.01745 Ω·mm² / m at 20°C, and 14.2 surface defects per 100 m. This is because when the coating thickness is less than 20mm, the copper liquid flow rate is higher than 0.80m / s, the settling residence time is less than 10s, and no filter is installed during the transfer stage, the copper liquid surface coverage is insufficient, the copper liquid flow disturbance increases, the settling time is insufficient, and the particle inclusions are not filtered and intercepted. The probability of copper liquid oxide film, scum and particle inclusions entering the continuous casting area increases, and the oxygen content of the finished copper rod and the internal defect area ratio of the billet increase accordingly.

[0158] In Comparative Example 3, the coating thickness during the transfer stage was 100 mm, exceeding the range of 20 mm to 80 mm in the method embodiment; the copper liquid flow rate was 0.10 m / s, lower than the range of 0.15 m / s to 0.80 m / s in the method embodiment; the settling residence time was 90 s, higher than the range of 10 s to 60 s in the method embodiment; and the filter element pore size was 50 ppi, higher than the range of 10 ppi to 40 ppi in the method embodiment. The finished copper rod of Comparative Example 3 had an oxygen content of 214 mg / kg, an internal defect area ratio of 0.88%, a volume resistivity of 0.01741 Ω·mm² / m at 20°C, and 13.4 surface defects per 100 m. This is because when the coating thickness during the transfer stage is higher than 80 mm, the copper liquid flow rate is lower than 0.15 m / s, the settling residence time is higher than 60 s, and the filter element pore size is higher than 40 ppi, the resistance to copper liquid transfer and the risk of temperature drop increase. The thermal stability of molten copper decreases when it enters the crystallization region, the solidification state changes during continuous casting, and the area ratio of internal defects in the billet and the number of surface defects on the finished copper rod increase.

[0159] In Comparative Example 2, the casting temperature was 1060°C, lower than the range of 1080°C to 1150°C in the method embodiment; the casting speed was 20 m / min, higher than the range of 6 m / min to 18 m / min in the method embodiment; the hot-cast billet exit temperature was 800°C, lower than the range of 850°C to 980°C in the method embodiment; and the rolling temperature was 720°C, lower than the range of 750°C to 950°C in the method embodiment. The finished copper rod of Comparative Example 2 had an oxygen content of 238 mg / kg, an internal defect area ratio of 1.10%, a volume resistivity of 0.01750 Ω·mm² / m at 20°C, and 17.0 surface defects per 100m. This is because when the casting temperature is below 1080°C, the casting speed is above 18 m / min, the hot-cast billet exit temperature is below 850°C, and the rolling temperature is below 750°C, a mismatch occurs between solidified shell growth, internal feeding, and the plastic deformation state of the hot-cast billet. Internal defects in the billet are extended or exposed during continuous rolling, resulting in an increase in the volume resistivity of the finished copper rod at 20°C and the number of surface defects.

[0160] In Comparative Example 4, the casting temperature was 1170℃, higher than the range of 1080℃ to 1150℃ in the method embodiment; the casting speed was 5 m / min, lower than the range of 6 m / min to 18 m / min in the method embodiment; the hot-cast billet exit temperature was 1000℃, higher than the range of 850℃ to 980℃ in the method embodiment; and the rolling temperature was 970℃, higher than the range of 750℃ to 950℃ in the method embodiment. The finished copper rod of Comparative Example 4 had an oxygen content of 252 mg / kg, an internal defect area ratio of 0.92%, a volume resistivity of 0.01744 Ω·mm² / m at 20℃, and a surface defect count of 15.1 per 100m. This is because when the casting temperature is higher than 1150℃, the casting speed is lower than 6m / min, the hot casting billet exit temperature is higher than 980℃ and the rolling temperature is higher than 950℃, the risk of oxide generation on the surface of the hot casting billet and adhesion on the rolling surface increases, the continuity of the solidification structure and the rolling structure is affected, and the oxygen content of the finished copper rod, the area ratio of internal defects in the billet and the number of surface defects of the finished copper rod are all in a high range.

[0161] Based on the preferred embodiments of the present invention described above, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for continuous casting and rolling of a low-oxygen, high-conductivity copper rod, characterized in that, Includes the following steps: S1: The copper raw materials are batched, tested, smelted, and kept warm to form a copper liquid with controlled temperature and oxidation state; S2: Covering protection, smooth flow guidance and inclusion blocking treatment are carried out in the copper liquid transfer path to form a low-oxygen and low-inclusion copper liquid; S3: Based on the temperature state and inclusion control state of the low-oxygen, low-inclusion copper liquid, match the continuous casting conditions and carry out continuous casting to form a hot cast billet with a temperature suitable for continuous rolling. S4: Perform surface condition treatment and confirm the rolling temperature for the hot-cast billet to form a suitable hot-cast billet for rolling. S5: Utilizing suitable hot-cast billets for continuous rolling, followed by cooling, cleaning, drying, protection, and coiling, a low-oxygen, high-conductivity copper rod is formed.

2. The method according to claim 1, characterized in that, In step S1, when testing the copper raw materials, the testing objects include the purity of the copper raw materials, the state of oil stains on the surface of the copper raw materials, the state of water accumulation on the surface of the copper raw materials, and the state of obvious non-copper foreign matter in the copper raw materials.

3. The method according to claim 1, characterized in that, In step S1, the melting temperature is 1120℃ to 1200℃, the thickness of the covering layer during the melting stage is 20mm to 80mm, the slag removal treatment is carried out after the copper raw material is completely melted, the holding temperature is 1100℃ to 1160℃, the holding time is 10min to 60min, the oxygen content of the copper liquid before casting is controlled to be 100mg / kg to 400mg / kg, and the thickness of the covering layer during the holding stage is 20mm to 80mm.

4. The method according to claim 1, characterized in that, In step S2, the protective coating acts on the surface of the molten copper in the runner, ladle and nozzle. The temperature of the molten copper during the transfer is 1080℃ to 1150℃. The thickness of the coating during the transfer stage is 20mm to 80mm. The temperature drop in the molten copper transfer path is no more than 40℃.

5. The method according to claim 1, characterized in that, In step S2, the flow rate of the molten copper in the copper transfer path is 0.15 m / s to 0.80 m / s, the fluctuation range of the molten copper level in the flow channel is within ±10 mm, and the copper transfer path is equipped with slag-blocking, settling, and filtering positions. The settling residence time is 10 s to 60 s, the filter element pore size is 10 ppi to 40 ppi, the slag-blocking position is set before the inlet of the gating nozzle, and the oxygen content control target before the low-oxygen, low-inclusion copper liquid enters the continuous casting area is 100 mg / kg to 400 mg / kg.

6. The method according to claim 1, characterized in that, In step S3, the continuous casting conditions include casting temperature, casting speed, crystallization cooling water temperature and crystallization cooling water pressure. The casting temperature is 1080℃ to 1150℃, the casting speed is 6m / min to 18m / min, the crystallization cooling water temperature is 20℃ to 45℃, the crystallization cooling water pressure is 0.15MPa to 0.45MPa, and the crystallization cooling water flow rate is 20m³ / h to 80m³ / h.

7. The method according to claim 1, characterized in that, In step S3, when the casting temperature is between 1120℃ and 1150℃, the casting speed is controlled between 6m / min and 12m / min; when the casting temperature is between 1080℃ and 1120℃, the casting speed is controlled between 10m / min and 18m / min.

8. The method according to claim 1, characterized in that, In step S3, the copper liquid level fluctuation range in the crystallization zone is within ±8mm, and the hot-cast billet exit temperature is 850℃ to 980℃.

9. The method according to claim 1, characterized in that, In step S4, the surface condition treatment is an online cleaning set between the outlet of the continuous casting unit and the inlet of the continuous rolling mill. The online cleaning method includes air cleaning or mechanical brushing. The air cleaning pressure is 0.20MPa to 0.60MPa, the mechanical brushing speed is 500r / min to 2000r / min, and the inlet temperature is 750℃ to 950℃.

10. The method according to claim 1, characterized in that, In step S5, the continuous rolling inlet temperature is 750℃ to 950℃, the single-pass reduction rate is 10% to 35%, the rolling speed is 5m / s to 25m / s, the target copper rod diameter is 8.0mm ± 0.3mm, the cooling and lubricating medium temperature is 20℃ to 45℃, the emulsion mass concentration is 1.0% to 4.0%, the cooling and lubricating medium pressure is 0.20MPa to 0.60MPa, the post-rolling cooling water temperature is 20℃ to 45℃, the post-rolling cleaning pressure is 0.20MPa to 0.80MPa, the surface temperature of the cooled copper rod is 40℃ to 90℃, the drying air pressure is 0.20MPa to 0.60MPa, the surface protective agent coating amount is 0.02g / m to 0.10g / m, and the winding tension is 50N to 300N.

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