Intelligent controllable atmosphere protection type annealing method

Abstract

The invention discloses an intelligent controllable atmosphere protection type annealing method. The method comprises the following steps: charging; pre-treating in a furnace; filling protective gas; and annealing, preserving heat, discharging and air-cooling. The designed cooling system is matched with the long-time low-temperature heat preservation effect of atmosphere protection gas to achieve the slow effect, compared with a natural cooling furnace body technology in the prior art, the process production quality effect is better, the oxidation effect of the surface of a copper conductor is reduced, and the actually-measured resistance value reducing effect is obvious; and the use efficiency and the expansion effect of the protective atmosphere are greatly improved.

Description

Technical Field

[0001] This invention relates to the field of annealing of copper conductors for cables, and particularly to an intelligent and controllable atmosphere-protected annealing method. Background Technology

[0002] Currently, the development of intelligent and controllable atmosphere-protected annealing equipment for copper conductor cables is very active. Its core objective is to efficiently process copper materials while ensuring a bright, oxidation-free surface, and to improve the overall intelligence level and energy efficiency of the process. It is generally equipped with a vacuum system, furnace body, and heating system.

[0003] However, in the existing technology, because the furnace body is naturally cooled and the cooling rate is relatively fast, the copper conductors produced are very prone to oxidation on the surface after production, resulting in technical problems such as high measured resistance and unstable quality of the produced copper conductors. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide an intelligent and controllable atmosphere-protected annealing method, which mainly solves the technical problem that the copper conductors produced by the original process have a high oxidation rate and inconsistent quality.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: In a first aspect, the present invention provides an intelligent and controllable atmosphere-protected annealing method, the specific steps of which are as follows: For furnace loading, the copper conductor to be processed is placed stably into a sealed stainless steel tube furnace, and the process flow information is preset in the control system. Pre-treatment inside the furnace: Close the furnace door or furnace cover of the sealed stainless steel tube furnace and ensure the seal of the sealed stainless steel tube furnace. Then remove the air inside the furnace and the surface of the copper conductor to maintain a vacuum inside the furnace. After pretreatment in the furnace, an inert or reducing gas with protective atmosphere properties is introduced under vacuum to further create an oxygen-free environment in the furnace until the pressure inside the furnace is higher than atmospheric pressure. Annealing and heat preservation are performed, the heating system is started, and heating is carried out according to the preset temperature rise curve; after heating is completed, the sealed stainless steel tube furnace is kept warm, and the heating system is used to precisely maintain the temperature stability of the stainless steel tube furnace through the control system. After the furnace is air-cooled, the heating system is stopped, and the cooling system located at the outlet section of the sealed stainless steel tubular furnace is started. A slow cooling zone is set up at the outlet section for initial cooling. A sealed water-cooling jacket is installed inside the furnace. After the furnace temperature drops to the target temperature, the sealed water-cooling jacket is started for secondary cooling. The protective atmosphere gas circulates inside the sealed water-cooling jacket to cool the furnace, achieving rapid cooling inside the furnace.

[0006] Preferably, it also includes water cooling, in which the workpiece is quickly immersed in a cooling water tank when it has been air-cooled to a specific temperature.

[0007] Preferably, the inert gas is high-purity nitrogen or argon, and the reducing gas is hydrogen or a nitrogen-hydrogen mixture; the protective atmosphere gas is introduced into the sealed stainless steel tube furnace through an atmosphere protection pipeline, and the specific introduction process is as follows: a small amount of gas is introduced to break the high vacuum state; the gas is continued to be introduced until the pressure inside the furnace is higher than atmospheric pressure to a positive pressure state of 0.01-0.03 MPa.

[0008] Preferably, the inner wall of the sealed water-cooled jacket is indirectly cooled by cooling water, and the temperature of the cooling water is adjusted by a control system.

[0009] Preferably, the control system includes a PLC unit, information acquisition sensors, and a recording module. The information acquisition sensors are used to collect the temperature, pressure, flow rate, and velocity of the protective atmosphere gas, as well as the annealing temperature, protective gas pressure, and cooling water temperature of the cooling system inside the sealed stainless steel tube furnace.

[0010] Preferably, in the annealing and heat preservation step, the heat preservation temperature is 190-220°C, and the heat preservation time is 650-720 min. In a second aspect, an intelligent controllable atmosphere-protected annealing system is provided to achieve the method of the first aspect, comprising: an annealing system for precisely heating to recrystallize the copper conductor, eliminate internal stress, restore its flexibility and conductivity, and introducing a protective gas inside the annealing system to isolate the copper conductor from contact with oxygen; a cooling system located at the rear of the annealing system, which uses adjustable two-stage cooling to rapidly and controllably cool the high-temperature conductor after annealing and lock in the annealed structure; a vacuum system, the negative pressure suction head of the vacuum system located inside the annealing system to create a negative pressure space inside the annealing system; and a control system for connecting and adjusting the power output intensity of the annealing system and the cooling system respectively, and collecting data from the annealing system and the cooling system through sensors, recording the date and material information of the copper conductor.

[0011] Preferably, the annealing system includes a sealed stainless steel tube furnace, a heating system disposed inside the sealed stainless steel tube furnace, an atmosphere protection pipeline, and a temperature control unit; the atmosphere protection pipeline is used to introduce high-purity nitrogen or a nitrogen-hydrogen mixture into the sealed stainless steel tube furnace; the temperature control unit is used to form a temperature control zone inside the sealed stainless steel tube furnace.

[0012] Preferably, the heating system is induction heating or infrared tube heating, and the temperature control zone includes a preheating zone, a constant temperature zone, and a slow cooling zone.

[0013] Preferably, the cooling system includes an in-furnace slow cooling zone located at the outlet section of a sealed stainless steel tubular furnace and a sealed water-cooled jacket, the sealed water-cooled jacket being indirectly cooled by cooling water.

[0014] Preferably, the control system includes a PLC unit, a human-machine interface touch screen for displaying and controlling PLC unit data, a closed-loop control unit for automatically adjusting parameters according to the PLC unit, a recording unit for recording production process information, and an early warning unit for emergency shutdown and abnormal alarm.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The cooling system designed in this invention, combined with the long-term low-temperature insulation effect of the protective atmosphere gas, achieves a slow effect. Compared with the existing natural cooling furnace technology, its process production quality is better, which reduces the oxidation effect on the surface of copper conductors and significantly reduces the measured resistance value, greatly improving the efficiency of the protective atmosphere and its extended application.

[0016] 2. This invention allows one person to operate the entire production line, reducing manual intervention and ensuring consistent product quality. The process formula can be easily switched via a touch screen, quickly adapting to the annealing requirements of copper conductors with different wire diameters (e.g., 0.5mm²-10mm²).

[0017] 3. This invention ensures that the conductor is free from oxidation and remains bright and new through atmosphere protection, with resistivity fully meeting the standards and excellent flexibility. It also adopts induction heating, which has high thermal efficiency, no oxidation throughout the process, no need for subsequent acid washing, and avoids acid pollution, thus conforming to the production concept of "environmentally friendly wires". Attached Figure Description

[0018] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is the overall process flow diagram of the present invention. Detailed Implementation

[0019] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0020] In Example 1, as Figure 1 As shown, the present invention provides an intelligent and controllable atmosphere-protected annealing method. The entire process mainly consists of: loading the furnace → sealing → vacuuming → filling with protective gas → annealing and heat preservation → air cooling after unloading → water cooling → storage. Before loading the furnace, a self-inspection of the target copper conductor and the sealed stainless steel tube furnace equipment is required before proceeding to the next step; the specific process flow is as follows: 1. Loading the furnace; Operators must wear protective equipment (gloves, safety helmets, etc.), inspect the surface of the copper conductor to ensure that there is no excessive impurities such as oil or moisture, and clean and dry it if necessary; The upper and lower layers are separated by a steel frame. When placing the copper conductor coils, avoid collisions with the furnace opening. The copper conductors need to be placed on a movable rack to prevent them from collapsing due to deformation or slippage during heating. Appropriate gaps should be left between the copper conductors to ensure smooth flow of protective gas. During furnace loading, the copper conductor wire data also needs to be recorded in the control system. 2. Seal; Operators should carefully clean the sealing grooves and sealing rings of the furnace door and furnace opening, ensuring they are free of debris and damage. The furnace door / cover should be closed smoothly, and all fastening bolts or locking devices should be tightened according to the operating procedures. All external interfaces, valves, and inspection ports should be checked to ensure they are in the correct position, ensuring the entire furnace body becomes a essentially sealed space.

[0021] 3. Vacuuming; Start the vacuum pump system to begin extracting air from the furnace chamber. The vacuum level inside the sealed stainless steel tube furnace continues to rise. When it reaches -0.1MPa, a large amount of residual air and moisture adsorbed on the surface of the workpiece will be removed. After reaching the preset vacuum level, maintain the pressure for 10 minutes to check the sealing performance of the furnace body. 4. Fill with protective gas; High-purity nitrogen or argon atmosphere protective gas is introduced into the vacuum space inside the sealed stainless steel tube furnace, and the gas intake is regulated through gas pipes and valves. First, a small amount of gas is introduced to break the high vacuum state; Then continue to purge until the pressure inside the furnace is 0.01-0.03 MPa higher than atmospheric pressure, and maintain the positive pressure. 5. Annealing and heat preservation; Heating stage: Start the heating system and start the preheating zone under the heating system. Heating is carried out according to the temperature rise curve preset by the control system. The heating rate needs to be strictly controlled by the control system. Too fast a heating rate will cause the temperature difference between the inside and outside of the workpiece to be too large, generating new thermal stress and even causing deformation. Holding stage: Once the furnace temperature reaches the preset annealing temperature (depending on the material, for example, 290°C for BVR products), the holding stage begins. The constant temperature zone under the heating system is activated, and the preheating zone is closed. During this period, the control system inside the furnace will precisely maintain a stable temperature through the heating system. The holding temperature is 190°C, and the holding time is 720 minutes, ensuring that all workpieces can reach the required temperature uniformly. 6. Air cooling inside the furnace In-furnace cooling: After the heat preservation is completed, the heating system is stopped first, and the cooling system is started in coordination. The cooling system has a slow cooling zone at the furnace outlet section, so that the copper conductor is cooled faster in the slow cooling zone according to the cooling curve of the control system. External cooling: When the furnace temperature is cooled to a safe lower temperature (e.g., <200°C, the specific temperature depends on the material and process requirements), it can be further cooled inside the furnace through a closed water-cooled jacket. The protective atmosphere gas will also be circulated into the closed water-cooled jacket in a synchronous manner, and the inner wall will be indirectly cooled through the cooling water to achieve the effect of secondary gas cooling. Through the above steps, the copper conductor has been annealed and manufactured. The purpose is to process conductors for high flame-retardant, high-temperature resistant, and environmentally friendly home decoration wires. Through atmosphere protection and precise temperature control, and with an unconventional cooling system in the rear half of the furnace, a slow cooling zone is set at the furnace outlet to avoid material stress changes caused by sudden temperature changes. A sealed water-cooling sleeve connected to the furnace door is installed inside the furnace. The slowly decreasing temperature allows the protective atmosphere to be in contact with the conductor surface for a long time, so that the copper conductor surface usually has a bright metallic color. This state indicates that the anti-oxidation effect formed by the protective atmosphere has adhered to the conductor surface, and no large amount of oxidation will occur under long-term use.

[0022] For specific material or process requirements, such as the need to fix high-temperature structures or rapidly pass through certain sensitive temperature ranges, the following steps are also required: 7. Water cooling; When the copper conductor is cooled to a specific temperature, it is quickly immersed in a water tank.

[0023] After completing all the above steps, there is still: 8. Storage; Cool to room temperature: Ensure that the copper conductors removed from the furnace have completely cooled to room temperature; Inspection: Check the appearance of the workpiece (whether it is shiny, whether it is deformed), elongation (using a tensile testing machine for random checks), etc. Rust prevention treatment: If the product will not proceed to the next process immediately, a simple oxidation treatment (such as applying a protective film) may be necessary. Identification and Recording: Mark qualified products, record furnace number, batch, process parameters and inspection results to achieve quality traceability; Storage environment: Store the workpieces in a dry, clean, designated area, stack them neatly, and avoid bumps and corrosion.

[0024] This technology increases cooling efficiency by rapidly cooling the protective atmosphere gas. Compared to existing natural cooling furnace technologies, it reduces process cycle time by more than 40%, significantly improving process efficiency while maintaining production quality. The specific details are shown in the table below. Comparative Example 1 Based on Example 1, after furnace annealing, the copper conductor is kept at a temperature of 320°C for 190 minutes; during air cooling, the copper conductor is directly removed and placed on a dry, windless surface for further air cooling.

[0025] Performance tests were conducted on Example 1 and Comparative Example 1 to compare the hardness and elongation of the copper conductors in Example 1 and Comparative Example 1. The changes in resistance before and after annealing were recorded. Then, it was observed whether oxidation occurred after the copper conductors were left for a long time after the annealing process. Copper conductors were manufactured in ten groups of furnaces, and their average values ​​were taken. The details are shown in the table below:

[0026] As shown in the table above, the hardness and elongation of both Example 1 and Comparative Example 1 are qualified. This is because the original process flow has not been significantly changed. In the data before and after annealing, the resistivity of the thinner diameter copper conductor decreases by at least 40%-52%, while that of the thicker diameter conductor decreases by 33%-50%. This is because the resistance of the thicker diameter copper conductor decreases significantly after the diameter increases, which slightly reduces the resistance caused by oxidation on the surface of the copper conductor. The data is also consistent with conventional physical phenomena. After the copper conductors were placed in the room temperature for the same period of time without any protective measures (10min-60min), only a small amount of oxidation occurred in Example 1, while the surface of Comparative Example 1 showed a large amount of oxidation. It can be seen that under long-term low-temperature holding conditions, slow cooling in the furnace can achieve better adhesion of the protective atmosphere to the surface of the copper conductor. This allows the protective atmosphere to not only protect the space inside the furnace but also increase the anti-oxidation effect of the copper conductor. Short-term high temperature cannot form a significant anti-oxidation effect on the surface of the copper conductor. At the same time, by adjusting the control system under this process, not only can the heating process be controlled more precisely, but the cooling process can also be adjusted, making the overall process intelligent and automated, without expanding into other complex process sequences. This allows the original production line to be used directly after simple modification, offering higher cost-effectiveness and shorter downtime.

[0027] In another embodiment, a smart and controllable atmosphere-protected annealing system is provided for implementing the method of the first embodiment, including: The annealing system is used to precisely heat the copper conductor to recrystallize, eliminate internal stress, restore its flexibility and conductivity, and introduce a protective gas inside the annealing system to isolate the copper conductor from oxygen. The annealing system includes a sealed stainless steel tube furnace, a heating system located inside the sealed stainless steel tube furnace, an atmosphere protection pipeline, and a temperature control unit. The furnace body adopts a sealed stainless steel tube furnace to ensure good airtightness at the furnace door; the heating system can be induction heating or infrared tube heating. The atmosphere protection pipeline mainly introduces atmosphere protection gas into the furnace body. The atmosphere protection gas is high-purity nitrogen (N2) or nitrogen-hydrogen mixture (N2+H2) as a protective atmosphere. It is mainly used to completely isolate oxygen, prevent copper conductors from oxidizing and turning black at high temperatures, keep the conductors bright, and significantly improve conductivity and surface quality. The temperature control unit has multiple temperature regulation zones inside the furnace, including a preheating zone, a constant temperature zone, and a slow cooling zone. The preheating zone and the constant temperature zone form output pipes for the heating system, while the slow cooling zone forms output pipes for the cooling system. The temperature control unit is intelligently regulated by PID control, and thermocouples monitor the furnace temperature in real time. The collected information is sent to the control system for unified display and regulation.

[0028] The cooling system, located behind the annealing system, uses adjustable two-stage cooling to rapidly and controllably cool the high-temperature conductor after annealing, thus locking in the annealed structure. The cooling system includes a slow cooling zone, located at the furnace outlet section, which prevents a sudden drop in internal temperature during slow cooling, thus avoiding changes in material stress. The furnace body is also equipped with a sealed water-cooled jacket, whose structure mainly cools the air by drawing in the internal protective atmosphere gas, while the inner wall of the sealed water-cooled jacket is indirectly cooled by cooling water.

[0029] The vacuum system, with its negative pressure suction nozzle located inside the annealing system, is used to create a negative pressure space within the annealing system. The control system is used to connect and adjust the power output of the annealing system and the cooling system respectively, and to collect data from the annealing system and the cooling system through sensors, and record the date and material information of the copper conductor.

[0030] The control system includes: The PLC unit and human-machine interface touch screen are mainly used for centralized setting and display of all parameters: annealing temperature, linear speed, protective gas flow rate, cooling water temperature, tension of each unit, etc. The closed-loop control unit is used to form a closed-loop control for key parameters (such as temperature, gas pressure, flow rate, and speed) and automatically adjust to maintain the stability of the furnace body; The recording unit is used to record historical production data (date, line gauge, process parameters, etc.) under the control system, which facilitates quality traceability and process optimization. The early warning unit is used in emergency situations, such as when a line is broken, the temperature is too high, the air pressure is insufficient, or the cooling water fails, to automatically alarm and shut down the machine.

[0031] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A smart, controllable atmosphere-protected annealing method, characterized in that, The specific steps are as follows: For furnace loading, the copper conductor to be processed is placed stably into a sealed stainless steel tube furnace, and the process flow information is preset in the control system. Pre-treatment inside the furnace: Close the furnace door or furnace cover of the sealed stainless steel tube furnace and ensure the seal of the sealed stainless steel tube furnace. Then remove the air inside the furnace and the surface of the copper conductor to maintain a vacuum inside the furnace. After pretreatment in the furnace, an inert or reducing gas with protective atmosphere properties is introduced under vacuum to further create an oxygen-free environment in the furnace until the pressure inside the furnace is higher than atmospheric pressure. Annealing and heat preservation are performed, the heating system is started, and heating is carried out according to the preset temperature rise curve; after heating is completed, the sealed stainless steel tube furnace is kept warm, and the heating system is used to precisely maintain the temperature stability of the stainless steel tube furnace through the control system. After the furnace is air-cooled, the heating system is stopped, and the cooling system located at the outlet section of the sealed stainless steel tubular furnace is started. A slow cooling zone is set up at the outlet section for initial cooling. A sealed water-cooling jacket is installed inside the furnace. After the furnace temperature drops to the target temperature, the sealed water-cooling jacket is started for secondary cooling. The protective atmosphere gas circulates inside the sealed water-cooling jacket to cool the furnace, achieving rapid cooling inside the furnace.

2. The intelligent controllable atmosphere-protected annealing method according to claim 1, characterized in that, It also includes: Water cooling involves rapidly immersing the workpiece in a cooling water bath once it has been air-cooled to a specific temperature.

3. The intelligent controllable atmosphere-protected annealing method according to claim 1, characterized in that, The inert gas is high-purity nitrogen or argon, and the reducing gas is hydrogen or a nitrogen-hydrogen mixture. The protective atmosphere gas is introduced into the sealed stainless steel tube furnace through a protective atmosphere pipeline. The specific introduction process is as follows: A small amount of gas is introduced to disrupt the high vacuum state; Continue filling with gas until the pressure inside the furnace reaches a positive pressure state of 0.01-0.03 MPa, which is higher than atmospheric pressure.

4. The intelligent controllable atmosphere-protected annealing method according to claim 1, characterized in that, The inner wall of the sealed water-cooled jacket is indirectly cooled by cooling water, and the temperature of the cooling water is regulated by a control system.

5. The intelligent controllable atmosphere-protected annealing method according to claim 3, characterized in that, The control system includes a PLC unit, information acquisition sensors, and a recording module. The information acquisition sensors are used to collect the temperature, pressure, flow rate, and velocity of the protective atmosphere gas, as well as the annealing temperature, protective gas pressure, and cooling water temperature of the cooling system inside the sealed stainless steel tube furnace.

6. The intelligent controllable atmosphere-protected annealing method according to claim 3, characterized in that, In the annealing and heat preservation step, the heat preservation temperature is 190-220°C and the heat preservation time is 650-720 min.

7. An intelligent controllable atmosphere-protected annealing system for implementing the methods of claims 1-6, characterized in that, include: The annealing system is used to precisely heat the copper conductor to recrystallize, eliminate internal stress, restore its flexibility and conductivity, and introduce a protective gas inside the annealing system to isolate the copper conductor from oxygen. The cooling system, located behind the annealing system, uses adjustable two-stage cooling to rapidly and controllably cool the high-temperature conductor after annealing, thus locking in the annealed structure. The vacuum system, with its negative pressure suction nozzle located inside the annealing system, is used to create a negative pressure space within the annealing system. The control system is used to connect and adjust the power output of the annealing system and the cooling system respectively, and to collect data from the annealing system and the cooling system through sensors, and record the date and material information of the copper conductor.

8. The intelligent controllable atmosphere-protected annealing method according to claim 7, characterized in that, The annealing system includes a sealed stainless steel tube furnace, a heating system located inside the sealed stainless steel tube furnace, an atmosphere protection pipeline, and a temperature control unit. The atmosphere protection pipeline is used to introduce high-purity nitrogen or a nitrogen-hydrogen mixture into the sealed stainless steel tube furnace. The temperature control unit is used to create a temperature control zone inside a sealed stainless steel tube furnace.

9. The intelligent controllable atmosphere-protected annealing method according to claim 8, characterized in that, The heating system is either induction heating or infrared tube heating, and the temperature control zone includes a preheating zone, a constant temperature zone, and a slow cooling zone.

10. The intelligent controllable atmosphere-protected annealing method according to claim 8 or 9, characterized in that, The cooling system includes an in-furnace slow cooling zone and a sealed water-cooled jacket located at the outlet section of the sealed stainless steel tubular furnace. The sealed water-cooled jacket is indirectly cooled by cooling water. The control system includes a PLC unit, a human-machine interface touch screen for displaying and controlling PLC unit data, a closed-loop control unit for automatically adjusting parameters according to the PLC unit, a recording unit for recording production process information, and an early warning unit for emergency shutdown and abnormal alarms.

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