With the rapid development of high-speed and high-precision battery electrode rolling equipment both at home and abroad, more and more research on simulation technology has been carried out to research the electrode plate rolling.This paper introduces the asymmetric coating battery electrode plate rolling simulation, simulation The results show that the hydraulic servo-pressure plate mill can roll asymmetrically coated battery plate and overcome the shortcomings that the gas-liquid booster pump pressurized battery pole plate mill can not roll normally. Technology in the hydraulic field and hot roller press research progress, and carried out a summary and its shortcomings.
introduction
In recent years, the vigorous development of new energy industry, lithium-ion battery industry has brought tremendous room for development, while the lithium-ion battery quality and life also put forward higher requirements in the lithium-ion battery production process, the pole piece The completion of the manufacture of the battery determines the performance of more than 80% .Therefore, the quality of positive and negative pieces of lithium-ion battery has a significant impact on the quality of the battery, the manufacture of pole piece occupies an important position in the battery manufacturing process.
A large number of studies at home and abroad show that the compaction density of the positive and negative electrodes has a great influence on the battery performance such as the capacity of the lithium ion battery. The suitable compaction density can increase the capacity of the battery, reduce the internal resistance and reduce the polarization loss The uniformity of the density and the consistency of the thickness of the rolled battery pole piece directly determine the service life of the battery and how much energy is stored, it can be seen that rolling the pole piece with a rolling mill is extremely important in the production of the pole piece A process, due to the pole piece mill on the importance of battery production, but also bound to require high-precision rolling equipment to automation.
The simulation technology is based on mathematical model, verification, experiment as the core, comprehensive computer technology, automatic control and system engineering, information processing technology and other disciplines.The general process of computer equipment simulation system is as follows:
(1) Establish the mathematical model of the control system studied.
(2) The mathematical model is transformed into a computer simulation model through simulation software.
(3) using the appropriate algorithm to write simulation programs or other programs directly.
(4) Through the simulation, get the system dynamic response curve and data.
(5) Analyze the system simulation results and put forward the methods and measures to improve the system dynamic performance.
With the continuous development of computer technology and science and technology, people can use simulation technology to analyze the dynamic performance of rolling mill equipment system conveniently, determine the optimal parameters and get the best equipment control system.The load characteristic of battery pole piece is nonlinear and the load of rolling process But also changes with time. The servo control system of the battery pole mill has nonlinearity and time-varying nature, so it is necessary to simulate the rolling process of the battery pole piece in order to understand the influence of various factors on the rolling quality and rolling efficiency Which has important theoretical guidance for the design of subsequent battery pole piece rolling mill.Therefore, the simulation technology has become one of the important auxiliary means for the design of equipment system of lithium rolling mill.
At home and abroad, more and more researches on rolling mill are made by simulation technology. Simulation and analysis of asymmetrical coated battery pole piece rolling is a typical subject of application of simulation technology. At the same time, many application problems of simulation technology in hydraulic field are proposed. , The application of simulation technology in hot roller press is also a subject of great concern.Therefore, this paper introduces and summarizes the following three aspects respectively.
1 Asymmetric Coated Battery Pole Rolling Simulation Analysis
The application of the battery electrode plate is symmetrical coating and asymmetric coating.Because the practical use of gas-liquid booster pump pressurized battery pole piece rolling mill to asymmetric coating battery pole piece rolling effect is poor, Beijing North China Innovative Energy Lithium Equipment Technology Co., Ltd. and Wang Yiqun, who co-operation of the Division Mill as the main research object, respectively, gas-liquid booster pump battery electrode plate and hydraulic servo-controlled pressurized pole piece mill Simulation Analysis of Symmetric Coated Battery Pole Rolling.
1.1 gas-liquid booster pump battery pole piece rolling mill
Gas-liquid booster pump pressure mode Battery electrode plate mill lower cost, capable of rolling symmetrically coated battery pole piece, but it uses wedge iron and screw off-line regulation of roll gap, the roll gap and rolling force can not be real-time Online adjustment, so that the rolling speed, the quality of the pole piece and the scope of application subject to a certain degree of constraints.
Based on the analysis of the structure and rolling characteristics of the gas-liquid booster pump pressurized battery pole piece, the simulation models of the battery pole piece model and the mill rolling pole piece process are shown in Figure 1. As the actual use of gas-liquid Booster pump pressurized battery pole piece mill asymmetric coating of the battery pole piece (the schematic diagram shown in Figure 2) the rolling effect is poor, the following simulation analysis of this situation, the simulation results shown in Figure 3 Show.
The simulation results show that when the pole piece is rolled from double to single, the rolling force acting on the pole piece decreases from 346 kN to 96 kN, and the density of the single layer can not meet the requirements. Is based on the two-tier part of the rolling needs offline setting, once set, can not be changed. The role of the rolling force on the single layer is determined by the roll and wedge iron stiffness is not adjustable. The greater the stiffness, the smaller the force acting on the monolayer.When the roll is rolled to the pole piece gap, the roller and the pole piece disengage, the force acting on the pole piece is zero.
1.2 Hydraulic servo control pressurized pole piece mill
Hydraulic servo control Pressing pole piece rolling mill is no longer using the wedge iron roll gap adjustment, the hydraulic cylinder pressure can be fully applied to the battery pole piece, in order to be able to real-time control of the role in the battery pole piece pressure and hydraulic cylinder piston position, the pressure system Valve-less cylinder hydraulic servo control system Without wedge iron, negative pre-roll rolling can be achieved when using position ring rolling, no longer using feeler gauges like gas-liquid booster pump pressurized pole piece mills Detection of roll gap, can only be set positive roll gap, to overcome the wedge iron due to the effective rolling force can not continue to increase the shortcomings.
Gas-liquid booster pump pressurized battery pole piece rolling mill can not be rolled asymmetrically coated battery pole piece, as in the rolling experiment did not asymmetrically coated battery pole piece, the researchers on the asymmetric coating conditions constant Simulation of the rolling force, the simulation results shown in Figure 4. It can be seen through the simulation results, the roll from the two-sided coating slurry partially rolled to one side coating portion, the rolling force has a reduced fluctuation , But can quickly return to the set value of the rolling force, to ensure that the rolling force is basically constant.Description can be used in the subject of the rolling mill designed such battery pole piece, to overcome the gas booster pump pressurized battery Shortcomings of pole piece mill.
Servo pressurized battery pole piece mill pressure settings can be adjusted online in real time, the asymmetric coating of the battery pole piece rolled, but also according to process requirements, so that the double-coated and single-coated place to use different Of the rolling force or different roll gap rolling, and further increase the scope of the mill.
The introduction of hydraulic servo control system with high transmission force and high power makes the pole sheet rolling mill realize the real-time adjustment of pressure and roll gap on-line. When rolling single-layer or double-layer pole pieces alternately, the single layer part can get better Rolling effect, making the quality of the rolling pole piece greatly improved.But due to the various forms of pole piece coating, pole piece gap suddenly thinner, pole pieces of the load mutation, or affect the rolling speed further. Sheet rolling mill with nonlinear and time-varying, battery pole piece load is also non-linear, but also on the mill's design and control challenges.
2 simulation technology in the field of hydraulic applications
The so-called hydraulic system simulation is to establish the mathematical model of the hydraulic system studied, and converted into a simulation model on the computer, and then solve the operation to analyze the dynamic and static characteristics of the process of the system.
Hydraulic system simulation can not only find out the defects of the existing system, put forward the improvement measures to the system, and make substantial improvements and amendments to the system. Moreover, some parameters in the system design process can be inspected and analyzed to ensure the system has a good Dynamic performance.In the actual project, the content of the research should be analyzed in the place where the system is most vulnerable.In this case, we should ignore some minor contradictions, highlight the main contradictions, make targeted and the key to solve the problem.
The key and difficult point of computer simulation of hydraulic system lies in establishing an accurate mathematical model to describe the hydraulic system and secondly developing a reasonable simulation program.The establishment of an accurate mathematical model is the foundation and precondition of the simulation.The main methods used to establish the mathematical model are mainly There are transfer function method, analytic modeling method and power bond graph method.
The application of simulation technology in the hydraulic field include the following aspects
(1) When designing the hydraulic system, the mathematical model of the designed hydraulic system is established through theoretical deduction. After simulation, the simulation data and experimental data are compared to verify the accuracy of the established mathematical model, and the verified mathematical model as the future The basis for improving and designing similar systems.
(2) Using the established mathematical model and simulation model, through the simulation experiment to determine the adjustment range of the known system parameters, thus shortening the system adjustment time and improving efficiency.
(3) Through the simulation experiment, the feasibility of the hydraulic system and the influence of each hydraulic component on the system are studied. Finally, the best component parameters and control scheme are obtained.
(4) The simulation technology is used to study the influence of the structural parameters of the newly designed components on the dynamic characteristics of the system, and to determine the appropriate structural parameters of the components.
The design of battery servo control system of battery pole piece rolling mill mainly solves the defect that traditional pole piece rolling mill relies on wedge iron screw rod to adjust roll gap to realize constant roll gap and constant rolling force and increase rolling speed.Using simulation verification The accuracy of the hydraulic servo system is designed and the measures to improve the performance of the pole mill's servo system are studied.
Dong Min and others in order to comprehensively study the dynamic characteristics of rolling mill thick gauge control system, establish an intuitive and realistic virtual rolling mill model, and propose a simulation method based on AMESim and ADAMS joint modeling.In the ADAMS, rigid-flexible coupling dynamics model of rolling mill entity is constructed, The load characteristics of the rolling mill are studied. The physical model of hydraulic system is established in AMESim, and the precise modeling and analysis of the hydraulic servo system are realized. The two data are exchanged through the interface, which ensures the accuracy of the hydraulic system simulation and the authenticity of the load system simulation. The real-time response of the system and real-time data of the exit slab thickness are obtained through the co-simulation model. The simulation output data and measured data are compared to prove that the simulation model can accurately reflect the dynamic response of the system and reflect the mechanical deformation under load and plate thickness Real-time output.
Liu et al. In order to improve the rolling efficiency and quality of the rolling mill, a dynamic simulation model of the hydraulic system was established. The load characteristic equation was given, and the rolling process such as constant rolling force and constant roll gap, simulation and experiment The results are basically the same.Based on the hydraulic servo-pressurized battery electrode plate mill of Beijing North China Innovative Energy Lithium-Ion Equipment Technology Co., Ltd., the hydraulic pressure system of the hydraulic servo pole-pressing mill is analyzed, and the hydraulic pump, accumulator And the valve of the dynamic simulation model, the simulation model, and made the corresponding experiments, the component model was experimentally verified.Based on the component model of the entire hydraulic system modeling, making the system model to consider The influence of hydraulic pump and accumulator on the pre-pressure of the servo valve and the effect of the pressure reducing valve on the servo cylinder's backpressure are analyzed.The dynamic simulation of the step response and the rolling process of the closed-loop rolling force is carried out on the model. The corresponding experiment was made on the pole piece mill. The simulation results are basically consistent with the experimental results, which verify the correctness of the model. The simulation model established has practical reference value, Parameter optimization control system provides an important basis.
3 simulation technology in hot roller press application
Hot roll press refers to a roll press capable of heating the roll, and when using the hot roll press to roll the pole piece, the compaction density, mass and production speed of the pole piece can be increased. The rolls are heated by different heating processes Heating process, the uniformity of the temperature distribution on the roller surface and the energy consumption were analyzed. Based on the analysis, the heating process, the uniformity of the temperature distribution on the roller surface and the thermal stress of the roller with different structure were analyzed, which could guide the on-site heating process, improve the roller structure, Improve the quality of pole piece rolling is of great significance.Studies on the roll at home and abroad are mainly divided into two aspects: 1) the way of heating the roll and its corresponding control system, the heating method of the roll mainly includes electric heating and oil heating; 2) roll temperature distribution and internal stress.
Wang Wencheng et al. Studied the electromagnetic field and temperature field of the cylinder under induction heating, pointed out that the electromagnetic heating has the characteristics of high precision and low energy consumption, and developed a roller induction heating system; Li Hui discussed the heating of the edge heater The application of rolling wide strip production, by heating the edge of the roll, is conducive to improving the crown accuracy of hot-rolled steel.
Shen Shijie and others using finite element software for universal mill for temperature analysis, thermal coupling analysis and fatigue life study, pointed out that the roll neck and roller body between the fillet is the location of thermal stress concentration, where the most dangerous, increase the roller The diameter and chamfer of the neck can make the stress concentration obviously improved. Hu Shicheng et al. Established the contact thermal conductivity model and the heat transfer mathematical model between the roll shell and the casting, and simulated the roll and slab. The roll roll The lower the roughness is, the stronger the thermal conductivity is. The stress analysis and modal analysis of the mill roll are carried out by Wang Yongzhou et al. The finite element software simulates the electroslag heating of the roll surface and the slag pool thermoelectric field , Analysis of the temperature distribution within the slag pool.
Wang Xingdong and others using heat transfer knowledge and finite element software simulation analysis method, by changing the distance between the lateral oil gallery and the roll surface δ, according to the same heating process for three different structures of the roll is heated. Given The internal strain diagram of the roll is shown in Fig. 5. The strain of the roll surface with δ = 70mm is 0.53mm / m and the strain of the roll surface with δ = 50mm is 0.61mm / m, which means the smaller the δ, the larger the deformation of the roll surface. Finite element software was used to analyze the temperature and stress of the roll. The results showed that the smaller the δ value, the shorter the heating time, the smaller the temperature difference of the roll face. The difference between the maximum stress and the strain of the three kinds of structure rolls was not significant. Road, the greater the stress, to improve the internal structure of the roller to provide a theoretical basis for the oil gallery.
In addition, through the roller surface and the internal temperature Figure 6 shows, the temperature of the oil inlet end of the roll is higher than the other end; both ends of the journal surface temperature reached 100 ℃ above, should choose high temperature bearing; roll body temperature distribution is more uniform, The temperature of the core is higher than the surface of the roller.The study also pointed out that the roll is equivalent to a collector, the longer the heating time, the smaller the heat absorption capacity of the roller to the HTF, the temperature difference between the oil inlet and outlet The smaller the energy lost by the HTF, the more uniform the temperature inside the roll, and the more uniform the roll surface temperature distribution.
Chen Guoliang and others established the oil heated roller model by using the finite element software and analyzed and calculated the three-dimensional temperature field of the hot roller. The analysis results show that the gradient of the temperature inside the roller is mainly the radial change, but some temperature gradient along Axial change and improve the temperature uniformity of the roll end can improve the roll temperature distribution uniformity.Li Lixin and others by measuring the surface temperature of the work roll, the use of finite element software to establish CSP work roll temperature field model, the study of the rolling process roll Of the temperature field.Cai Hui invented a mainly for heating roller roll temperature control system, the thermal oil control in a certain temperature range, at the same time can be introduced into the roller room temperature heat conducting oil, heat conducting oil is sealed in the system, not Contact with the magnesium alloy strip, does not have any impact on its production, thermal oil will not pollute the environment, so that the roll temperature control in the appropriate range, improve product yield and production efficiency, rolling out the product of good quality.
Denis et al. Used the finite element software to analyze the thermal stress and fatigue life of roll in hot roll press. Luks et al. Analyzed the contact stress and roll surface temperature by experiments.
In summary, the temperature field, stress field and service life of the roll are currently studied more, it is necessary to further analysis of the oil-heated rolls such as roll surface temperature distribution, heating process and energy consumption, stress and strain , Such as the number of oil on the roller roll surface temperature difference, the heating process and stress effects.
4 Conclusion
The experimentally verified battery pole piece rolling mill model, the asymmetric coating of the battery pole piece virtual rolling, the simulation results show that the gas-liquid booster pump pressurized electrode pole rolling mill can not be normal rolling Cloth battery pole piece, and the hydraulic servo-pressurized battery pole piece rolling mill can roll similar battery pole piece.The application of simulation technology provides an effective model platform for the improvement of hydraulic control strategy.The heating process and the stress on the roll To be in-depth simulation analysis.
In the process of simulation analysis, changing the parameters of the model can simulate the changes of various components, mechanical components and other parameters in the actual physical system, so as to understand the influence of these actual parameters on the whole system and find out the main factors that affect the system performance. Are very conducive to the improvement of equipment design, improve equipment performance, shorten the design cycle, increase efficiency for special control systems, but also in simulation model control algorithm simulation experiments, to explore better control of the system to improve performance Algorithm, reducing the time and financial resources to conduct multiple physical experiments.
In the process of theoretical calculation and simulation analysis, many assumptions are taken and the experimental correlation method is used to solve the problem. Therefore, the boundary conditions in the simulation analysis need to be further corrected.
