A multi-layer pressure composite system of copper and stainless steel composite strips

Abstract

This application relates to the field of metal composite material preparation technology, specifically disclosing a multi-layer pressure composite system for copper-stainless steel composite strips. The system aims to address the shortcomings of existing technologies in the preparation of multi-layer copper-stainless steel composite strips in terms of interfacial bonding strength, uniformity, thickness control, residual stress, and warpage deformation. The system includes modules for raw material pretreatment, multi-layer stacking calibration, preheating, multi-stage pressure composite, cooling and leveling, and central control and monitoring. Through integrated, refined control and synergy of these modules, the system effectively promotes atomic diffusion at the copper-stainless steel interface, forming a stable metallurgical bond, suppressing residual stress, and significantly improving the manufacturing quality and production efficiency of the composite strips.

Description

Technical Field

[0001] This invention belongs to the field of metal composite material preparation technology, specifically relating to a multilayer pressure composite system of copper and stainless steel composite strips. Background Technology

[0002] Metal composite material technology, as an important material preparation method, aims to combine two or more metals with different properties through special processes to obtain materials with comprehensive performance that combine the advantages of each component. It is widely used in aerospace, electronics, and automotive manufacturing. Among them, single- and double-sided copper composite sheets and strips, due to their high conductivity, high mechanical strength, wear resistance, and corrosion resistance, have broad application prospects in the electrical industry. They are key materials for manufacturing high-performance electrical components, effectively improving the overall performance and service life of electrical appliances.

[0003] Among them, copper-stainless steel composite strips represent an important development direction in the field of metal composite materials. They aim to combine the excellent electrical and thermal conductivity of copper with the good strength and corrosion resistance of stainless steel to meet the demands of specific industrial applications for high-performance, multifunctional composite materials. Multilayer pressure bonding, as an important preparation technology, provides a feasible way to achieve a tight bond between these dissimilar metals, aiming to promote metallurgical bonding at the interfaces of different metals through the action of mechanical force.

[0004] However, existing technologies for preparing copper-stainless steel composite strips, especially those based on multi-layer pressure bonding systems, still face numerous challenges. Dissimilar metals, such as copper and stainless steel, exhibit significant differences in physicochemical properties (e.g., hardness, coefficient of thermal expansion, plastic deformation behavior), leading to defects such as weak interfacial bonding, delamination, voids, and even cracks during pressure bonding, severely impacting the overall performance and service life of the composite strip. Simultaneously, the multi-layer bonding process places higher demands on the deformation coordination, thickness uniformity, and overall thickness accuracy control of each layer. Existing composite systems often struggle to achieve precise control, resulting in significant fluctuations in product quality. Furthermore, residual stress generated during the bonding process is difficult to eliminate effectively, also negatively affecting the mechanical properties of the composite strip and reducing its reliability. Therefore, a multi-layer pressure bonding system that can effectively overcome these problems and achieve high bonding strength, high uniformity, and high efficiency in copper-stainless steel composite strips is urgently needed. Summary of the Invention

[0005] To address the shortcomings of existing technologies in the manufacturing of single- and double-sided copper composite strips, particularly for multi-layer copper-stainless steel composite strips, in achieving high conductivity, high mechanical strength, wear resistance, and corrosion resistance while ensuring the metallurgical bonding strength, interface uniformity, thickness control precision, and production efficiency between different metal layers (such as copper and stainless steel), as well as problems such as residual stress and warping deformation caused by differences in the thermophysical properties of dissimilar metals, this invention proposes a multi-layer pressure composite system for copper-stainless steel composite strips. This invention aims to fundamentally improve the manufacturing quality and efficiency of multi-layer copper-stainless steel composite strips through integrated and refined process control and equipment synergy.

[0006] According to one aspect of the present invention, a multi-layer pressure bonding system for copper-stainless steel composite strips is provided for preparing copper-stainless steel composite strips with a preset number of layers and thickness ratio. This system ensures a stable metallurgical bond between the copper and stainless steel layers through collaborative operation, while maintaining the overall mechanical and electrical properties of the composite strip. The system includes: a raw material unwinding and pretreatment module, a multi-layer stacking and calibration module, a preheating module, a multi-stage pressure bonding module, a cooling and leveling module, a shearing and winding module, and a central control and monitoring module. These modules work closely together to form a continuous automated production line.

[0007] In one embodiment of the present invention, the raw material unwinding and pretreatment module is used for initial treatment of the copper strip and stainless steel strip to be composited. This module includes: multiple independently controlled unwinding machines for separately conveying the copper strip and stainless steel strip; each unwinding machine is equipped with a tension control unit to ensure constant tension of the strip during the unwinding process to avoid slack or overstretching; a surface cleaning unit for removing oil, oxide layers, and other impurities from the strip surface; this unit includes a mechanical brushing device, an ultrasonic cleaning tank, a chemical degreasing tank, and a multi-stage rinsing and hot air drying device to ensure a clean strip surface and improve the activity of the subsequent bonding interface; and a surface activation unit for forming a uniform, pollution-free active layer on the strip surface to enhance the bonding ability of the interface; this unit can employ plasma treatment equipment or a high-precision belt grinding device to precisely control surface roughness and activity.

[0008] Furthermore, the multi-layer stacking and calibration module is used to precisely stack and align the pre-treated copper strips and stainless steel strips according to a preset layer sequence. This module includes: multiple independent tension adjustment mechanisms for precisely controlling the tension of each layer of strip entering the stacking area, ensuring the synchronicity of each layer before lamination; a high-precision guide roller group for precisely guiding the strips in the horizontal and vertical directions to prevent skewing; and an optical or laser alignment sensing system for real-time monitoring of the lateral position deviation of each layer of strip and automatic correction via a servo motor-driven fine-tuning device, ensuring precise alignment of each layer of strip before lamination. This module enables the alternating stacking of copper strips and stainless steel strips to form three-, five-, or more-layer composite structures.

[0009] In one embodiment of the present invention, the preheating module is used to heat the multilayer stacked strip to the temperature range required for solid-state bonding before pressure bonding. This module employs an induction heating furnace or a resistance heating furnace to provide a uniform and controllable heating environment. The heating furnace is equipped with a multi-zone independent temperature control system, which uses multiple infrared thermometers to monitor the surface temperature of the strip in real time and feeds the data back to the heating power supply, achieving precise closed-loop temperature control. The heating temperature range is precisely set within a specific range above the recrystallization temperature of copper and stainless steel but far below their melting points to promote atomic diffusion and lattice rearrangement while avoiding melting or excessive softening; typically, the heating temperature is controlled between 550°C and 850°C.

[0010] Furthermore, the multi-stage pressure composite module is the core component of this system, used to apply high pressure to the preheated multi-layer strip, enabling it to achieve metallurgical bonding under plastic deformation. This module comprises at least two stages of rolling mill stands connected in series. Each rolling mill stand consists of a pair of high-strength alloy steel rolls with finely ground and hardened surfaces, exhibiting high wear resistance and surface finish. The reduction of each pair of rolls is precisely controlled by an independent hydraulic or electric servo reduction mechanism, ensuring uniform and stable rolling force. High-precision pressure sensors are installed below the rolls to monitor the rolling pressure in real time and feed the data back to the central control system for real-time adjustment. The rolling speed is driven by a variable frequency motor, achieving synchronous coordination of each stage of the rolling mill stand and ensuring tension balance of the strip during the composite process. The first stage of rolling primarily achieves preliminary bonding between the strips and provides a larger reduction rate to activate interfacial atoms; subsequent stages of rolling further refine the grains, eliminate interfacial voids, and enhance interfacial bonding strength at lower reduction rates. The total reduction rate and the distribution of reduction rates at each stage are precisely calculated and set based on the total thickness of the composite strip, the number of layers, the type of material, and the required bonding strength. During the rolling process, the roll temperature is controlled by an internal cooling system to prevent overheating that could lead to roll deformation or strip adhesion.

[0011] In one embodiment of the present invention, the cooling and leveling module is used to cool the composite strip after pressure bonding and to mechanically level it. This module includes: a multi-stage cooling device that uses air jetting, atomized spraying, or cooling roller contact to controllably cool the composite strip, thereby reducing the strip temperature, fixing its internal structure, and effectively reducing residual stress caused by the difference in thermal expansion coefficients between copper and stainless steel; and a tension straightener or multi-roll straightener to eliminate internal stress generated during the bonding and cooling process, improve the straightness of the strip, and correct any slight warping or wavy edges. The tension or rolling pressure during the straightening process is precisely adjusted according to the material properties and the state of the strip.

[0012] Furthermore, the shearing and winding module is used for the final processing of the composite strip after lamination and leveling. This module includes: a precision trimming shear for removing irregular edges on both sides of the composite strip to ensure the accuracy of the composite strip's width and edge quality; a fixed-length flying shear or disc shear for cutting the composite strip to specific lengths according to production needs, or slitting it according to subsequent processing requirements; and a high-precision winding machine equipped with a tension taper control system and a swing guide device for neatly and tightly winding the trimmed or slid composite strip into a roll, avoiding surface damage and uneven end faces.

[0013] In one embodiment of the present invention, the central control and monitoring module serves as the "brain" of the entire system, responsible for centralized control, data acquisition, status monitoring, and fault diagnosis of all sub-modules. This module includes: an industrial computer or programmable logic controller (PLC) as the main controller, running specially developed control algorithms and a human-machine interface; a multi-channel data acquisition system for receiving massive amounts of data in real time from various modules (such as tension sensors, temperature sensors, pressure sensors, thickness gauges, width measuring instruments, and defect detection systems); advanced control algorithms, including but not limited to PID control, fuzzy control, or machine learning-based adaptive control algorithms, to precisely adjust various actuators (such as unwinding machine speed, furnace power, roll reduction, cooling intensity, and straightening amount) based on real-time data and preset process parameters, achieving closed-loop control; and a visual human-machine interface (HMI) for operators to set process parameters, monitor production status, view historical data, and perform fault diagnosis. This module also has data storage, trend analysis, and production report generation functions, providing data support for process optimization.

[0014] Throughout the lamination process, the central control and monitoring module acquires key parameters in real time, including but not limited to: the input tension of each layer of copper and stainless steel strips, obtained through tension sensors; the strip temperature in each area of ​​the preheating furnace, obtained through infrared thermometers; the rolling pressure and roll gap of each rolling stand in the multi-stage pressure lamination module, obtained through pressure and displacement sensors; the real-time thickness of the lamination strip, obtained through X-ray or laser thickness gauges; the width and edge condition of the lamination strip, obtained through a CCD vision measurement system; and surface defect information of the lamination strip, obtained through a surface defect detection system. The central control and monitoring module uses this data for comprehensive analysis through internal algorithms and adjusts relevant equipment parameters in real time. For example, when the lamination strip thickness exceeds the preset tolerance range, the system automatically adjusts the reduction of the corresponding rolling stand until the thickness returns to normal. When misalignment of each layer of strip is detected, the system adjusts the guiding device for correction. When the preheating temperature fluctuates, the system adjusts the heating power to maintain the set temperature. This real-time, multi-parameter collaborative feedback control mechanism ensures the stability and consistency of the lamination strip product quality.

[0015] The multi-layer pressure bonding system for copper-stainless steel composite strips can effectively promote atomic diffusion at the interface between copper and stainless steel by precisely controlling the interface bonding conditions, including the surface activity of pretreatment, the uniform heating temperature before bonding, the precise reduction rate and reduction force during multi-stage rolling, and the controlled cooling process after bonding, forming a dense metallurgical bonding layer. At the same time, it significantly suppresses residual stress and delamination risk caused by the difference in thermal expansion coefficients of the two metals.

[0016] Compared with the prior art, the advantages and positive effects of the present invention are as follows: This invention provides a multi-layer pressure bonding system for copper-stainless steel composite strips. Through its integrated and precise design, it significantly improves the production quality and efficiency of multi-layer copper-stainless steel composite strips. In the raw material pretreatment stage, the system ensures extremely high surface cleanliness and activity of the copper and stainless steel strips through multi-stage cleaning and surface activation, laying a solid foundation for subsequent metallurgical bonding. This greatly enhances the strength and uniformity of the bonding interface, effectively avoiding poor bonding problems caused by surface impurities or oxide layers in traditional processes.

[0017] Furthermore, the multilayer stacking and calibration module adopts a high-precision alignment sensing system and servo-driven fine-tuning device, which realizes the centimeter-level or even sub-millimeter-level precise alignment of each layer of strip material before entering the composite area. This solves the problem of insufficient accuracy of traditional manual alignment or simple mechanical guidance, and effectively avoids the increase in product scrap rate and the instability of composite strip width caused by interlayer misalignment.

[0018] As a positive effect of this invention, the preheating module utilizes a multi-zone independently temperature-controlled induction heating or resistance heating furnace, combined with an infrared thermometer for real-time closed-loop temperature control. This ensures that the strip reaches the optimal solid-phase bonding temperature range before entering the pressure bonding process, and that the temperature distribution is highly uniform. This precise temperature control greatly promotes atomic diffusion at the interface between copper and stainless steel, forming a denser and stronger metallurgical bonding layer, while avoiding bonding defects caused by localized overheating or underheating.

[0019] As a positive effect of this invention, the multi-stage pressure composite module employs at least two stages of rolling mill stands connected in series. Each rolling mill stand is equipped with an independent precision hydraulic or electric servo pressing mechanism and a high-precision pressure sensor. This multi-stage progressive composite strategy can apply optimal rolling pressure in stages, avoiding strip tearing or uneven plastic deformation that may be caused by a single large reduction. Precise control of reduction and rolling force, combined with optimized rolling speed, ensures the coordination of plastic flow in the composite strip throughout the composite process, effectively suppresses the generation of residual stress, and significantly improves the interfacial bonding strength and the overall mechanical properties of the composite strip.

[0020] As a positive effect of the present invention, the cooling and leveling module effectively controls the cooling rate of the composite belt through a controllable multi-stage cooling device and a tension straightener or multi-roller straightener, and promptly eliminates the internal stress caused by the difference in thermal expansion coefficients between copper and stainless steel, significantly improving the straightness and dimensional stability of the composite belt, avoiding defects such as warping and wavy edges, thereby reducing the difficulty and cost of subsequent processing.

[0021] As a positive effect of this invention, the central control and monitoring module, by integrating a multi-channel data acquisition system, advanced control algorithms, and a visual human-machine interface, achieves automated and intelligent management of the entire production process. The system can monitor all key process parameters in real time and perform adaptive adjustments and fault diagnosis based on preset algorithms, significantly improving the automation level and operational stability of the production line, reducing the need for manual intervention and uncertainties in the production process, thereby increasing production efficiency, reducing energy consumption and scrap rates, and ensuring the continuous stability and consistency of product quality.

[0022] In summary, the multi-layer pressure composite system for copper-stainless steel composite strip proposed in this invention achieves a high degree of automation and precise control in all stages from material pretreatment to final winding. It effectively solves key technical challenges such as interface bonding strength, uniformity, residual stress control, and production efficiency in the multi-layer composite process of dissimilar metals, providing an advanced, efficient, and stable solution for manufacturing high-performance, high-reliability multi-layer copper-stainless steel composite strips. Attached Figure Description

[0023] Figure 1This is a schematic diagram of the overall technical solution architecture of the multi-layer pressure composite system of copper and stainless steel composite strip proposed in this invention. Figure 2 This is a schematic diagram of the core principle framework of multi-level pressure composite and central control and monitoring in this invention. Detailed Implementation

[0024] Please refer to Figure 1 and Figure 2 This embodiment discloses a multi-layer pressure bonding system for copper-stainless steel composite strips. This system aims to prepare copper-stainless steel composite strips with a preset number of layers and precise thickness ratios. Through collaborative operation, the system ensures a stable metallurgical bond between the copper and stainless steel layers, while maintaining the overall mechanical and electrical properties of the composite strip. As a continuous automated production line, the system comprises closely cooperating modules including a raw material unwinding and pretreatment module, a multi-layer stacking and calibration module, a preheating module, a multi-stage pressure bonding module, a cooling and leveling module, a shearing and winding module, and a central control and monitoring module.

[0025] The raw material unwinding and pretreatment module is used for the initial treatment of the copper and stainless steel strips to be laminated. The operation of this module is fundamental to the quality control of the entire lamination process. This module includes multiple independently controlled unwinding machines, a surface cleaning unit, and a surface activation unit.

[0026] Multiple independently controlled unwinding machines are specifically designed to separately transport copper and stainless steel strips. Each unwinding machine is equipped with an independent tension control unit, the core function of which is to ensure that the tension of the strip remains constant during the unwinding process, thereby preventing slack, overstretching, edge deformation, or curling of the strip during transport. The tension control unit typically uses high-precision sensors, such as strain gauge sensors or piezoelectric sensors, to detect the actual tension of the strip in real time. The data from these sensors is fed back to a high-performance servo drive system in real time. The servo drive system precisely adjusts the drive torque and speed of the unwinding machine based on the deviation between the preset tension target value and the actual detected value, achieving closed-loop tension control. For example, when the detected tension is lower than the set value, the system will slightly increase the drive torque to tighten the strip; conversely, when the tension is higher than the set value, the system will slightly decrease the drive torque. The typical range of tension setpoints for copper strips may be between 200 and 500 Newtons, while for stainless steel strips, due to their higher strength and modulus of elasticity, the tension setpoint may be between 300 and 700 Newtons. These settings are precisely calculated and verified based on the strip width, thickness, material grade, and the requirements of subsequent lamination processes to ensure that each layer of strip enters the subsequent processing stage in optimal condition.

[0027] The surface cleaning unit is crucial for ensuring the strength of the metal-to-metal bond. This unit thoroughly removes oil, oxide layers, and other impurities from the strip surface. It is equipped with a mechanical brushing device, an ultrasonic cleaning tank, a chemical degreasing tank, and a multi-stage rinsing and hot air drying system. The mechanical brushing device typically consists of multiple sets of rotating brush rollers made of nylon, steel wire, or special fibers. By adjusting the roller speed and contact pressure with the strip surface, large particles and loose oxides are effectively scraped away. A low-foaming water-based cleaning agent is used during the brushing process to enhance the cleaning effect. The ultrasonic cleaning tank utilizes high-frequency ultrasound to create cavitation in the cleaning solution, forming numerous tiny bubbles. The bursting of these bubbles generates shock waves, thoroughly removing stubborn oil, fine particles, and other contaminants from the microscopic crevices of the strip surface. The cleaning solution is typically a mixture of deionized water and a specialized ultrasonic cleaning agent, with the temperature controlled between 40°C and 60°C. The chemical degreasing tank uses a strongly alkaline or neutral degreasing solution. Through chemical dissolution, emulsification, and saponification, it efficiently removes organic contaminants such as animal and vegetable oils, mineral oils, and cutting fluids from the strip surface. The concentration and temperature of the degreasing solution (e.g., 60°C to 80°C) and the strip immersion time are precisely controlled to achieve optimal degreasing results while avoiding corrosion of the strip substrate. The multi-stage rinsing system typically includes at least three cascaded overflow rinsing tanks, using purified water to repeatedly rinse the strip and thoroughly remove residual cleaning agents and chemical degreasing solutions. After each rinsing stage, the strip passes through squeeze rollers or air scrapers to reduce water loss. Finally, the hot air drying system uses high-pressure clean hot air (e.g., temperature controlled between 80°C and 120°C) to quickly and thoroughly dry the strip, ensuring a completely clean surface free of water stains and residues, thereby improving the activity and bonding quality of subsequent bonding interfaces. The entire cleaning process incorporates a cleaning solution circulation, filtration, and regeneration system to ensure the continuous cleanliness and environmentally friendly treatment of the cleaning solution.

[0028] The surface activation unit is used to form a uniform, contamination-free active layer on the strip surface to enhance interfacial bonding. This unit can employ plasma treatment equipment or high-precision belt grinding equipment. Plasma treatment equipment introduces an inert gas (such as argon) or reactive gas (such as nitrogen or hydrogen) into a high-vacuum environment and generates low-temperature plasma under the action of a high-frequency electric field. High-energy ions and free radicals in the plasma bombard the strip surface, physically removing atomic-level contaminants while inducing surface atoms to rearrange, forming an active layer with higher surface energy and more active chemical bonds. The parameters of plasma treatment include gas flow rate, radio frequency power, treatment time, and treatment temperature, which are precisely controlled to achieve optimal activation effects; for example, the treatment time is typically between 10 and 60 seconds. High-precision belt grinding equipment uses ultra-fine grit abrasive belts to perform micro-cutting on the strip surface, removing the outermost oxide layer and microscopic defects, exposing a fresh, clean metal substrate. Grinding depth and surface roughness are precisely controlled by belt grit size, grinding pressure, and belt transport speed. For example, the surface roughness Ra value is controlled between 0.2 and 0.8 micrometers to provide sufficient micro-bonding area while avoiding excessive damage to the belt. Both activation methods can significantly improve the bonding activity of the belt surface, providing favorable conditions for subsequent metallurgical bonding.

[0029] The multi-layer stacking and calibration module is used to precisely stack and align pre-treated copper and stainless steel strips according to a preset layer sequence. The accuracy of this module directly affects the interlayer thickness uniformity and overall quality of the composite strip. This module includes multiple independent tension adjustment mechanisms, high-precision guide roller groups, and optical or laser alignment sensing systems.

[0030] Multiple independent tension adjustment mechanisms are used to precisely control the tension of each layer of strip as it enters the stacking area, ensuring synchronization of each layer before lamination. Similar to the tension control of the unwinding machine, but here the tension adjustment mechanisms are typically located closer to the stacking point, providing more precise fine-tuning capabilities. These mechanisms, driven by independent servo motors and precision reducers, combined with high-sensitivity tension sensors, enable independent and dynamic adjustment of the transmission speed and tension of each layer of strip. For example, the system can compensate for speed errors in real time by adjusting the rotational speed of the tension adjustment mechanisms based on the instantaneous speed differences of each layer of strip, ensuring that each layer of strip has a consistent linear velocity when entering the stacking point, thereby avoiding interlayer slippage or uneven stretching. The tension adjustment accuracy is typically ±5 Newtons, ensuring that interlayer synchronization errors are within a very small range.

[0031] High-precision guide roller assemblies are used to precisely guide the strip in both horizontal and vertical directions, preventing skewing. These assemblies typically consist of multiple precision-machined guide rollers with hardened and polished surfaces, resulting in an extremely low coefficient of friction and high wear resistance. The position and angle of the guide rollers are adjusted at the micrometer level using high-precision linear actuators or rotary encoders. The system precisely configures the guide roller assembly based on preset strip width and interlayer positional relationships, ensuring that each layer of strip maintains a strictly parallel and perpendicular position before entering the stacking area. The guide roller assembly also integrates a oscillation mechanism, which further eliminates any minor lateral fluctuations that may exist within the strip itself through small-range left-right oscillations.

[0032] Optical or laser alignment sensing systems are used to monitor the lateral position deviation of each layer of strip in real time and automatically correct it using a servo motor-driven fine-tuning device. Alignment sensing systems typically employ multiple high-resolution CCD cameras or laser displacement sensor arrays. The CCD cameras are arranged along the width of the strip, capturing real-time images of the strip edges and calculating the precise lateral position of the strip using image processing algorithms. The laser displacement sensors, on the other hand, non-contactly measure the distance between the strip edge and a baseline by emitting a laser beam and receiving the reflected signal. Data from these sensors is transmitted to a central control and monitoring module at millisecond-level frequencies. The central control and monitoring module calculates the correction amount based on the deviation between the real-time alignment data and the preset target position. This correction amount is sent to the servo motor-driven fine-tuning device via a high-speed data bus. The fine-tuning device typically consists of a high-precision ball screw and a servo motor, driving corresponding guide rollers or correction mechanisms to perform lateral displacement adjustments at the centimeter or even sub-millimeter level. For example, when the system detects that a copper strip layer has deviated 0.5 mm from the preset centerline to the left, the fine-tuning device will immediately activate, moving the copper strip 0.5 mm to the right to restore precise alignment. This closed-loop alignment system ensures that the lateral alignment accuracy of each strip layer reaches ±0.1 mm before entering the preheating module. This module can achieve alternating stacking of copper and stainless steel strips to form three-layer structures (e.g., stainless steel-copper-stainless steel), five-layer structures (e.g., stainless steel-copper-stainless steel-copper-stainless steel), or more composite structures to meet the specific requirements of different applications for conductivity, mechanical strength, and corrosion resistance.

[0033] The preheating module is used to heat the multilayer stacked strips to the temperature range required for solid-phase bonding before pressure bonding. A uniform and controllable heating environment is crucial to ensuring interfacial atomic diffusion and metallurgical bonding. This module employs an induction heating furnace or a resistance heating furnace.

[0034] Induction heating furnaces generate eddy current and hysteresis losses within the strip using high-frequency electromagnetic fields, enabling rapid and uniform heating of the strip itself. The furnace body consists of multiple induction coils, each powered by an independent frequency converter, achieving zoned heating. Resistance heating furnaces, on the other hand, generate radiant and convective heat through high-temperature resistance wires, transferring heat to the strip. The furnace body contains multiple independent heating zones, each equipped with an independent heating element and power controller. Both types of furnaces feature optimized furnace chamber structures and insulation materials to minimize heat loss and improve heating efficiency.

[0035] The heating furnace is equipped with a multi-zone independent temperature control system. This system uses multiple infrared thermometers to monitor the surface temperature of the strip in real time, without contact. The infrared thermometers are arranged along the width and length of the strip, forming a temperature monitoring array to obtain a temperature distribution map of the strip surface. Data from these thermometers is fed back to the heating power supply in real time at a high frequency (e.g., 10 times per second). Based on the deviation between the real-time temperature data and the preset target temperature, the heating power supply precisely adjusts the heating power of each heating zone using a proportional-integral-derivative (PID) control algorithm or a more advanced adaptive control algorithm, achieving precise closed-loop temperature control. The heating temperature range is precisely set within a specific range above the recrystallization temperature of copper and stainless steel but well below their melting points to promote atomic diffusion and lattice rearrangement while avoiding melting or over-softening. For copper-stainless steel composite strips, the heating temperature is typically controlled between 550°C and 850°C. For example, the recrystallization temperature of copper is typically between 200°C and 400°C, and the recrystallization temperature of stainless steel is typically between 800°C and 1000°C. Controlling the temperature within this range ensures that both materials are in a state of good plasticity and active atomic diffusion, without melting, thus creating optimal conditions for subsequent pressure bonding. Temperature control precision is typically required to reach ±5℃ to ensure the uniformity of the internal microstructure of the strip.

[0036] The multi-stage pressure composite module is the core component of the entire system, used to apply high pressure to the preheated multi-layer strip, enabling it to achieve metallurgical bonding under plastic deformation. This module comprises at least two stages of rolling mill stands connected in series.

[0037] Each rolling mill stand consists of a pair of high-strength alloy steel rolls. The roll surfaces undergo fine grinding and hardening treatments, such as carburizing, nitriding, or quenching, to achieve extremely high surface hardness (HRC60 or higher), high wear resistance, and excellent surface finish. The roll diameter and length are optimized based on the width of the composite strip and the rolling force requirements to ensure good rigidity and stability under high-speed, high-pressure rolling.

[0038] The reduction of each pair of rolls is precisely controlled by an independent hydraulic or electric servo reduction mechanism. The hydraulic reduction mechanism applies and adjusts the rolling force through high-pressure cylinders, and precisely controls the displacement of the cylinder pistons via proportional servo valves, thereby adjusting the roll gap. The electric servo reduction mechanism uses a high-precision servo motor to drive a reducer and ball screw, achieving micron-level adjustment of the roll gap. The control accuracy of the reduction mechanism typically reaches ±0.01 mm, ensuring that the rolling force acts uniformly and stably on the composite strip. High-precision pressure sensors, such as piezoelectric or strain gauge pressure sensors, are installed below the rolls to monitor the rolling pressure in real time and feed the data back to the central control and monitoring module at a high sampling rate (e.g., once per millisecond) for real-time adjustment. The rolling speed is driven by a variable frequency motor, achieving synchronous coordination of each rolling stand to ensure tension balance of the strip during the composite process. The variable frequency motor precisely adjusts the roll speed through vector control or direct torque control, maintaining strict synchronization with the strip transport speed.

[0039] The initial rolling stage primarily achieves preliminary bonding between strips and provides a significant reduction rate to activate interfacial atoms. In the initial rolling stage, the rolling pressure is typically high, for example, 500 to 1000 MPa per centimeter width, and the reduction rate may be set between 20% and 40%. This higher reduction rate allows for significant plastic deformation of copper and stainless steel, breaking down the oxide film at the interface, exposing fresh metal surfaces, and achieving initial contact and bonding of two or more strip layers at a macroscopic level. Subsequent rolling stages further refine the grains, eliminate interfacial porosity, and enhance interfacial bonding strength at lower reduction rates. In subsequent rolling stages, the rolling pressure and reduction rate gradually decrease; for example, the reduction rate may be set between 5% and 15% to avoid excessive deformation. Lower reduction rates help further promote atomic diffusion and lattice rearrangement at the interface, eliminating micropores or inhomogeneous regions that may have formed during the initial rolling stage, and improving the density and uniformity of the interfacial bonding.

[0040] The total reduction ratio and the distribution of reduction ratios at each level are precisely calculated and set based on the total thickness, number of layers, material type, and required bonding strength of the composite tape. This calculation process is typically based on the plastic deformation characteristics, recrystallization behavior, and performance requirements of the target product. For example, for composite tapes requiring extremely high bonding strength, a higher total reduction ratio and a more refined multi-level distribution strategy may be employed.

[0041] During the rolling process, the roll temperature is controlled by an internal cooling system to prevent overheating that could lead to roll deformation or strip adhesion. The cooling system typically includes internal circulating water cooling channels. Precision temperature sensors monitor the roll surface temperature in real time and adjust the flow rate and temperature of the cooling water to maintain the roll temperature within a preset range (e.g., 40°C to 80°C). Precise control of the roll temperature is crucial for maintaining roll geometry, extending roll life, and preventing strip from sticking to the rolls at high temperatures.

[0042] To achieve precise control and adaptive adjustment of the composite strip thickness during rolling, the central control and monitoring module employs a feedback adjustment algorithm. This algorithm adjusts the roll reduction based on real-time thickness deviation. Assuming the target thickness is... Real-time thickness measurement Thickness deviation is Roll reduction adjustment amount It can be calculated using the following formula: In this formula, Represents the proportionality coefficient. Represents the integral coefficient. These represent differential coefficients. These coefficients are optimized and tuned based on the system's dynamic response characteristics and process requirements; they work together to ensure that thickness deviations can be eliminated quickly and stably. Proportional term. Ensure the system responds instantly to current thickness deviations; the larger the deviation, the larger the adjustment. (Integral term) The aim is to eliminate long-standing steady-state deviations and prevent the system from continuously deviating from the target thickness. Differential term This is used to predict deviation trends, provide proactive control, suppress thickness fluctuations, and improve the system's dynamic response speed and stability. Through this real-time feedback adjustment mechanism, the system can control the final thickness of the composite tape within a very small tolerance range (e.g., ±0.02 mm), ensuring product dimensional accuracy.

[0043] The cooling and leveling module is used to cool the composite strip after pressure bonding and to mechanically level it. This module is crucial for eliminating residual stress, fixing the internal structure, and improving the straightness of the strip. The module includes a multi-stage cooling system and a tension straightener or multi-roll straightener.

[0044] The multi-stage cooling system employs methods such as air jetting, atomized spraying, or cooling roller contact to achieve controlled cooling of the composite strip. Air jetting uses a high-pressure fan to uniformly spray clean, ambient or low-temperature air onto the surface of the composite strip, carrying away heat. The speed and direction of the airflow are optimized to ensure uniform cooling. Atomized spraying utilizes atomizing nozzles to evenly spray tiny water droplets onto the surface of the composite strip. The evaporation of these droplets carries away a significant amount of heat, achieving efficient cooling. The flow rate and temperature of the sprayed water are controlled by precision valves to prevent excessively rapid localized cooling that could lead to strip deformation. Cooling roller contact involves direct contact between the composite strip and metal rollers containing internally circulating cooling water or oil, achieving efficient heat conduction cooling. The temperature of the cooling rollers is precisely controlled by an internal coolant circulation system. The multi-stage cooling system can reduce the strip temperature in stages, stabilize its internal structure, and effectively reduce residual stress caused by the difference in thermal expansion coefficients between copper and stainless steel. Controlling the cooling rate is crucial; excessively rapid cooling may lead to greater residual stress, while excessively slow cooling will affect production efficiency. The system monitors the surface temperature of the composite belt in real time using an infrared thermometer and dynamically adjusts the intensity of each cooling device according to a preset cooling curve to ensure that the cooling process is controlled and optimized.

[0045] Tension straighteners or multi-roll straighteners are used to eliminate internal stress generated during the lamination and cooling process of composite strips, improve the straightness of the strip, and correct any slight warping or wavy edges. Tension straighteners apply tensile stress to the composite strip, causing it to plastically extend within its elastic deformation range, thereby eliminating internal elastic stress and improving straightness. The stretching amount is precisely controlled by the speed difference between the front and rear sets of tension rollers. Multi-roll straighteners consist of multiple straightening rollers arranged alternately. The composite strip is repeatedly bent and deformed between these rollers, releasing residual stress within the material and achieving the purpose of straightening. The number, diameter, spacing, and roller gap adjustment of the straightening rollers are precisely set according to the material properties, thickness, and straightness requirements of the composite strip. The stretching amount or roller pressure during the straightening process is precisely adjusted according to the material properties and strip condition. For example, the elastic modulus and yield strength of copper-stainless steel composite strips differ significantly, and the setting of straightening parameters needs to comprehensively consider the synergistic deformation behavior of the two materials. This mechanical straightening method can achieve a flatness accuracy of 0.5 millimeters per meter for the composite belt, significantly improving product quality.

[0046] The shearing and winding module is used for the final processing of the composite tape after lamination and leveling. This module ensures the dimensional accuracy and packaging quality of the final product. This module includes precision trimming shears, fixed-length flying shears or circular shears, and a high-precision winding machine.

[0047] Precision trimming shears are used to remove irregular edges from both sides of the composite tape, ensuring the accuracy of the tape's width and the quality of its edges. The trimming shears typically consist of two sets of high-speed rotating shears. The shear gap and overlap are adjusted at the micrometer level using high-precision servo motors and encoders to accommodate trimming requirements for tapes of varying thicknesses. The trimming speed is strictly synchronized with the tape's transport speed to ensure smooth cutting, neat edges, and no burrs or tears. The trimmed waste edges are automatically collected and sent to a recycling system.

[0048] Fixed-length flying shears or disc shears are used to cut composite tape to specific lengths according to production needs, or to slit it according to subsequent processing requirements. Fixed-length flying shears use high-speed reciprocating shears to laterally cut the tape during high-speed movement, achieving fixed-length cutting. The cutting length is precisely measured by an encoder, with a control accuracy of ±1 mm. Disc shears consist of multiple sets of circular shears; by adjusting the spacing between the shears, the composite tape can be longitudinally cut into multiple narrow strips. The material and blade angle of the shears are specially designed to ensure a smooth and flat cut surface.

[0049] The high-precision winding machine is equipped with a tension taper control system and a swing guide device to neatly and tightly wind up the trimmed or slit composite strip into a roll. The tension taper control system gradually reduces the winding tension as the roll diameter increases to prevent excessive radial pressure on the inner layer of strip, which could cause plastic deformation or interlayer slippage, while ensuring the tightness of the outer layer. Tension sensors monitor the winding tension in real time and feed it back to the winding machine's drive motor, achieving closed-loop tension control. For example, the tension taper factor is typically set between 0.8 and 0.95. The swing guide device ensures that the strip is evenly distributed across the width of the roll during winding by reciprocating left and right, preventing misalignment of the strip edges that could lead to poor roll shape or end-face damage. The winding machine's operating parameters, including winding speed, tension, taper factor, and swing frequency, are precisely set and optimized by the central control and monitoring module according to product specifications and material characteristics.

[0050] The central control and monitoring module is the core intelligent unit of the entire system, responsible for centralized control, data acquisition, status monitoring, and fault diagnosis of all sub-modules. This module ensures the automation and intelligence of the production process and the stable consistency of product quality.

[0051] At the core of this module is an industrial computer or programmable logic controller (PLC) as the main controller, running specially developed control algorithms and a human-machine interface. Industrial computers typically employ high-performance multi-core processors, large-capacity storage, and real-time operating systems to meet the real-time computational requirements of complex control algorithms. PLCs, on the other hand, possess extremely high reliability, anti-interference capabilities, and flexible programming capabilities, making them suitable for harsh industrial environments.

[0052] A multi-channel data acquisition system is used to receive massive amounts of data from various modules in real time. The system includes analog input modules, digital input modules, and high-speed counting modules. These modules are connected to various sensors distributed throughout the production line, such as tension sensors, temperature sensors, pressure sensors, thickness gauges, width measuring instruments, and surface defect detection systems. For example, tension sensors acquire the input tension of each layer of copper and stainless steel strip in real time, with a data sampling frequency of up to 1000 Hz. The strip temperature in each area of ​​the preheating furnace is acquired using an infrared thermometer with an accuracy of ±1℃. The rolling pressure of each rolling stand in the multi-stage pressure composite module is acquired using pressure sensors, the roll gap is acquired using high-precision displacement sensors, and the thickness is measured in real time in a non-contact manner using X-ray or laser thickness gauges with micron-level accuracy. The width and edge condition of the composite strip are acquired using a CCD vision measurement system with an accuracy of ±0.1 mm. Surface defect information of the composite strip is acquired using a surface defect detection system composed of a high-resolution linear array camera and image processing algorithms. All collected data is transmitted to the central control and monitoring module via high-speed industrial Ethernet (such as Ethernet / IP or Profinet) or fieldbus (such as Profibus or CANopen) to ensure the real-time performance and integrity of data transmission.

[0053] Advanced control algorithms are the core of achieving closed-loop control and adaptive adjustment. These algorithms include, but are not limited to, PID control, fuzzy control, or machine learning-based adaptive control algorithms. These algorithms precisely adjust various actuators (such as unwinder speed, furnace power, roll reduction, cooling intensity, and straightening amount) based on real-time data and preset process parameters. For example, when an X-ray thickness gauge detects that the real-time thickness of the composite strip exceeds the preset tolerance range, the central control system immediately invokes the thickness control algorithm to calculate the precise roll reduction adjustment value and adjusts the roll gap of the corresponding rolling mill stand through the servo system until the thickness returns to normal. When the CCD vision measurement system detects alignment deviations in each layer of strip, the system adjusts the guide device for correction. When an infrared thermometer detects preheating temperature fluctuations, the system adjusts the heating power to maintain the set temperature.

[0054] For example, for the temperature control of the preheating furnace, the system employs a hybrid algorithm combining fuzzy logic and PID control. Its core principle is to dynamically adjust the heating power based on the real-time temperature deviation and its rate of change. Assuming the target temperature is... Real-time temperature measurement is Temperature deviation is The rate of change of deviation The fuzzy control section uses a preset fuzzy rule base to... and Fuzzification and inference yield a fuzzy output. This fuzzy output can be defuzzified into a power correction value. Meanwhile, a traditional PID controller, based on... and Generate a power correction amount The final power adjustment amount This can be obtained through a weighted average or other fusion strategy: In this formula, and These are weighting coefficients, which can be dynamically adjusted based on the system's operating status and expert experience. This hybrid control strategy combines the robustness of fuzzy control to nonlinear systems and uncertainty handling with the precision and stability of PID control, thereby achieving rapid response and high-precision control of heating temperature, ensuring that the strip reaches the optimal solid-phase composite temperature range before entering pressure composite.

[0055] A visual human-machine interface (HMI) is used by operators to set process parameters, monitor production status, view historical data, and diagnose faults. HMIs typically use large touchscreens to provide an intuitive graphical interface. Operators can use the HMI to view the real-time operating status of each module, trend curves of key parameters, alarm information, and fault diagnosis prompts. HMIs also have data storage, trend analysis, and production report generation functions, providing data support for process optimization. For example, they can analyze historical production data to identify process bottlenecks and optimize parameter settings, thereby improving production efficiency and product quality.

[0056] Throughout the lamination process, the real-time performance and accuracy of key parameters acquired by the central control and monitoring module are crucial for the system's efficient operation. These parameters include the input tension of each layer of copper and stainless steel strips, obtained through tension sensors; the strip temperature in each area of ​​the preheating furnace, obtained through infrared thermometers; the rolling pressure and roll gap of each rolling stand in the multi-stage pressure lamination module, obtained through pressure and displacement sensors; the real-time thickness of the lamination strip, obtained through X-ray or laser thickness gauges; the width and edge condition of the lamination strip, obtained through a CCD vision measurement system; and surface defect information of the lamination strip, obtained through a surface defect detection system. The central control and monitoring module utilizes this high-precision, high-frequency data for comprehensive analysis using internally integrated advanced control algorithms. When the lamination strip thickness exceeds the preset tolerance range, the system automatically adjusts the reduction of the corresponding rolling stand until the thickness returns to normal. When misalignment of each layer of strip is detected, the system adjusts the guiding device for correction. When the preheating temperature fluctuates, the system adjusts the heating power to maintain the set temperature. This real-time, multi-parameter collaborative feedback control mechanism ensures the stability and consistency of composite strip product quality. Through refined monitoring and adaptive control of these key parameters, this system can significantly suppress problems such as residual stress and warping deformation that may occur during the multilayer composite process of dissimilar metals, and ensure that the composite strip achieves extremely high standards in terms of interface bonding strength, uniformity, thickness control accuracy, and production efficiency.

[0057] The multi-layer pressure bonding system for copper-stainless steel composite strips proposed in this invention can effectively promote atomic diffusion at the interface between copper and stainless steel by precisely controlling the interface bonding conditions, including the surface activity of pretreatment, uniform heating temperature before bonding, precise reduction rate and force during multi-stage rolling, and controlled cooling process after bonding. This results in the formation of a dense metallurgical bonding layer, while significantly suppressing residual stress and delamination risks caused by the difference in thermal expansion coefficients of the two metals. The integrated design and refined control of the system fundamentally improve the manufacturing quality and efficiency of multi-layer copper-stainless steel composite strips, providing an advanced, efficient, and stable solution for the production of high-performance composite materials.

Claims

1. A multi-layer pressure composite system for copper and stainless steel composite strips, characterized in that, include: The raw material unwinding and pretreatment module is used to perform initial treatment on the copper strip and stainless steel strip to be composited. The initial treatment includes tension control, surface cleaning and surface activation. The multi-layer stacking and calibration module is used to precisely stack and align the copper strip and stainless steel strip after the initial treatment according to a preset layer order. The alignment includes real-time monitoring of lateral position deviation and automatic correction. The preheating module is used to heat the multi-layer stacked strip to the temperature range required for solid-phase composite before pressure bonding. The heating process has independent temperature control and real-time monitoring in multiple zones. A multi-stage pressure composite module is used to apply high pressure to a preheated multi-layer strip to achieve metallurgical bonding under plastic deformation. The multi-stage pressure composite module includes at least two stages of rolling mill stands connected in series, and the reduction amount of each stage of the rolling mill stand can be independently and precisely controlled. The multi-stage pressure composite module consists of at least two series-connected rolling mill stands, each stage of which is composed of a pair of high-strength alloy steel rolls. The surface of the rolls is finely ground and hardened. The reduction of each pair of rolls is precisely controlled by an independent hydraulic or electric servo reduction mechanism. A high-precision pressure sensor is installed below the rolls to monitor the rolling pressure in real time and feed it back to the central control and monitoring module for real-time adjustment. The multi-stage pressure composite module has a first-stage rolling process used to achieve initial bonding between strips and provide a large reduction rate to activate interface atoms, with the reduction rate set between 20% and 40%. Subsequent rolling stages are used to further refine grains, eliminate interface voids, and enhance interface bonding strength at a lower reduction rate, with the reduction rate set between 5% and 15%. During the rolling process, the roll temperature is controlled by an internal cooling system. The cooling and leveling module is used to controllably cool and mechanically level the composite strip after pressure bonding in order to reduce residual stress and improve flatness. The shearing and winding module is used to trim the edges, cut or slit the composite tape after lamination and leveling, and rewind it with high precision. The central control and monitoring module performs centralized control, data acquisition, status monitoring, and fault diagnosis of the above modules, and adjusts each actuator based on real-time data and preset process parameters through advanced control algorithms.

2. The multi-layer pressure composite system of copper and stainless steel composite strips according to claim 1, characterized in that, The raw material unwinding and pretreatment module includes: multiple independently controlled unwinding machines for conveying copper strip and stainless steel strip respectively, each unwinding machine being equipped with a tension control unit to ensure constant tension of the strip during the unwinding process; a surface cleaning unit for removing oil, oxide layer and other impurities from the surface of the strip, the surface cleaning unit including a mechanical brushing device, an ultrasonic cleaning tank, a chemical degreasing tank and a multi-stage rinsing and hot air drying device; and a surface activation unit for forming a uniform, pollution-free active layer on the surface of the strip, the surface activation unit employing plasma treatment equipment or a high-precision belt grinding device.

3. The multi-layer pressure composite system of copper and stainless steel composite strips according to claim 1, characterized in that, The multi-layer stacking and calibration module includes: multiple independent tension adjustment mechanisms for precisely controlling the tension of each layer of strip entering the stacking area to ensure the synchronicity of each layer before lamination; a high-precision guide roller group for precisely guiding the strip in the horizontal and vertical directions to prevent skewing; and an optical or laser alignment sensing system for real-time monitoring of the lateral position deviation of each layer of strip and automatic correction via a servo motor-driven fine-tuning device.

4. The multi-layer pressure composite system of copper and stainless steel composite strips according to claim 1, characterized in that, The preheating module adopts an induction heating furnace or a resistance heating furnace, and has a multi-zone independent temperature control system. The temperature control system monitors the surface temperature of the strip in real time through multiple infrared thermometers and feeds it back to the heating power supply to achieve precise closed-loop temperature control. The heating temperature range is controlled between 550℃ and 850℃.

5. The multi-layer pressure composite system of copper and stainless steel composite strips according to claim 1, characterized in that, The cooling and leveling module includes: a multi-stage cooling device that uses air jet, atomized spray or cooling roller contact to controllably cool the composite strip, thereby reducing the strip temperature and the residual stress caused by the difference in thermal expansion coefficients between copper and stainless steel; and a tension straightener or multi-roller straightener to eliminate the internal stress generated by the composite strip, improve the straightness of the strip, and correct warping or wavy edges.

6. The multi-layer pressure composite system of copper and stainless steel composite strips according to claim 1, characterized in that, The shearing and winding module includes: a precision trimming shear for cutting off irregular edges on both sides of the composite tape; a fixed-length flying shear or disc shear for cutting the composite tape into specific lengths or slitting it; and a high-precision winding machine equipped with a tension taper control system and a swing guide device for neatly and tightly winding the trimmed or slitted composite tape into a roll.

7. The multi-layer pressure composite system of copper and stainless steel composite strips according to claim 1, characterized in that, The central control and monitoring module includes: an industrial computer or programmable logic controller as the main controller, running control algorithms and a human-machine interface; a multi-channel data acquisition system for receiving real-time operating data from each module; an advanced control algorithm for precisely adjusting each actuator based on real-time data and preset process parameters to achieve closed-loop control; and a visual human-machine interface for operators to set process parameters, monitor production status, view historical data, and perform fault diagnosis.

8. The multi-layer pressure composite system of copper and stainless steel composite strips according to claim 7, characterized in that, The central control and monitoring module is used to acquire in real time the input tension of each layer of copper strip and stainless steel strip, the strip temperature in each area of ​​the preheating furnace, the rolling pressure and roll gap of each rolling stand in the multi-stage pressure composite module, the real-time thickness of the composite strip, the width and edge condition of the composite strip, and the surface defect information of the composite strip. The acquired data is then comprehensively analyzed by an internal algorithm. When the thickness of the composite strip is detected to exceed the preset tolerance range, the reduction of the corresponding rolling stand is automatically adjusted. When the alignment deviation of each layer of strip is detected, the guide device is adjusted to correct the deviation. When the preheating temperature fluctuates, the heating power is adjusted to maintain the set temperature.

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