Research and Development Trend of Shape Control for Cold Rolling Strip

Shape is an important quality index of cold rolling strip. Up to now, many problems in the shape control domain have not been solved satisfactorily, and a review on the research progress in the shape control domain can help to seek new breakthrough directions. In the past 10 years, researches and applications of shape control models, shape control means, shape detection technology, and shape con- trol system have achieved significant progress. In the aspect of shape control models, the researches in the past improve the accuracy, speed and robustness of the models. The intelligentization of shape control models should be strengthened in the future. In the aspect of the shape control means, the researches in the past focus on the roll opti- mization, mill type selection, process optimization, local strip shape control, edge drop control, and so on. In the future, more attention should be paid to the coordination control of both strip shape and other quality indexes, and the refinement of control objective should be strengthened. In the aspects of shape detection technology and shape control system, some new types of shape detection meters and shape control systems are developed and have successfully indus- trial applications. In the future, the standardization of shape detection technology and shape control system should be promoted to solve the problem of compatibility. In general,the four expected development trends of shape control for cold roiling strip in the future are intelligentization, coordi- nation, refinement, and standardization. The proposed research provides new breakthrough directions for improv- ing shape quality.

Application of Smith Predictor Based on Single Neural Network in Cold Rolling Shape Control

Flatness is one of the most important criterion factors to evaluate the quality of the steel strip. To improve the strip＇ s flatness quality, the most frequently used methodology is to employ the closed-loop automatic shape control system. However, in the shape control system, the shape-meter is always installed at the down way of the exit of the cold rolling mill and can not sense the changes of the strip flatness in the rolling gap directly. This kind of installation results in the delay of the feedback in the control system. Therefore, the stability and response performance of the system are strongly affected by the delay. At present, there is still no mature way to design controllers for systems with time delay. Although the conventional PID controller used in most practical applications has the capability to compensate the delay, the effect of the compensation is limited, especially for the systems with long time delay. Smith predictor, as a compensator for solving this problem, is now widely used in industry systems. However, the request of highly precise model of the system and the poor adaptive performance to the changes of related parameters limit the application of the Smith predictor in practice. In order to overcome the drawbacks of the Smith predictor, a new Smith predictor based on single neural network PID （SNN-PID） is proposed. Because the single neural network is employed into the Smith predictor to improve the controller＇s self-adaptability, the adaptive capability to the varying parameters of the system is improved. Meanwhile, for the purpose of solving the problems such as time-consuming and complicated calculation of the neural networks in real time, the learning coefficient of neural network is divided into several stages as usually done in expert control system. Therefore, the control system can obtain fast response due to the improved calculation speed of the neural networks. In order to validate the performance of the proposed controller, the experiment is conducted on the shape control system in a 300 mm four-high reversing cold rolling mill. The experimental results show that the SNN-PID with Smith predictor controller can effectively compensate the delay effects and achieve better control performance than the conventional PID controller.

Experimental Study on Characteristics of NiMnGa Magnetically Controlled Shape Memory Alloy

The static and dynamic magnetic controlling characteristics of NiMnGa magnetically controlled shape memory alloy （MSMA） were experimentally studied. The results show that the characteristics of induced strain with respect to the magnetic field are nonlinear with saturation nature, and dependent on the temperature as well as the load applied to the MSMA. The magnetic shape memory effect can be observed only in complete martensite phase at room temperature. The magnetic permeability of MSMA is not constant and reduces with the increment of magnetic field. The relative saturation magnetic permeability of MSMA is about 1.5.

Fuzzy Shape Control Based on El man Dynamic Recursion Network Prediction Model

In the strip rolling process, shape control system possesses the characteristics of nonlinearity, strong coupling, time delay and time variation. Based on self adapting Elman dynamic recursion network prediction model, the fuzzy control method was used to control the shape on four-high cold mill. The simulation results showed that the system can be applied to real time on line control of the shape.

Advances in Compact Manufacturing for Shape and Performance Controllability of Large-scale Components-A Review

Research on compact manufacturing technology for shape and performance controllability of metallic components can reanze the simplification and high-reliability of manufacturing process on the premise of satisfying the requirement of macro/micro-structure. It is not only the key paths in improving performance, saving material and energy, and green manufacturing of components used in major equipments, but also the challenging subjects in frontiers of advanced plastic forming. To provide a novel horizon for the manufacturing in the critical components is significant. Focused on the high-performance large-scale components such as bearing rings, flanges, railway wheels, thick-walled pipes, etc, the conventional processes and their developing situations are summarized. The existing problems including multi-pass heating, wasting material and energy, high cost and high-emission are discussed, and the present study unable to meet the manufacturing in high-quality components is also pointed out. Thus, the new techniques related to casting-rolling compound precise forming of rings, compact manufacturing for duplex-metal composite rings, compact manufacturing for railway wheels, and casting-extruding continuous forming of thick-walled pipes are introduced in detail, respectively. The corresponding research contents, such as casting ring blank, hot ring rolling, near solid-state pressure forming, hot extruding, are elaborated. Some findings in through-thickness microstructure evolution and mechanical properties are also presented. The components produced by the new techniques are mainly characterized by fine and homogeneous grains. Moreover, the possible directions for fin＇ther development of those techniques are suggested. Finally, the key scientific problems are first proposed. All of these results and conclusions have reference value and guiding significance for the integrated control of shape and performance in advanced compact manufacturing.

Shape control technology during electrochemical synthesis of gold nanoparticles

Gold nanoparticles with different shapes and sizes were prepared by adding gold precursor （HAuC14） to an electrolyzed aqueous solution of poly（N-vinylpyrrolidone） （PVP） and KN03, which indicates the good reducing capacity of the PVP-containing solution after being treated by electrolysis. Using a catholyte and an anolyte as the reducing agents for HAuC14,＇ respectively, most gold nanoparticles were spherical particles in the former case but plate-like particles in the latter case. The change in the pH value of electrolytes caused by the electrolysis of water would be the origin of the differences in shape and morphology of gold nanoparticles. A hypothesis of the H＋ or OH- catalyzed PVP degradation mechanism was proposed to interpret why the pH value played a key role in determining the shape or morphology of gold nanoparticles. These experiments open up a new method for effectively controlling the shape and morphology of metal nanoparticles by using electrochemical methods.

Adaptive Shape Control for Thermal Deformation of Membrane Mirror with In-plane PVDF Actuators

Optical membrane mirrors are promising key components for future space telescopes. Due to their ultra-thin and high flexible properties, the surfaces of these membrane mirrors are susceptible to temperature variations. Therefore adaptive shape control of the mirror is essential to maintain the surface precision and to ensure its working performance. However, researches on modeling and control of membrane mirrors under thermal loads are sparse in open literatures. A 0.2 m diameter scale model of a polyimide membrane mirror is developed in this study. Three Polyvinylidene fluoride(PVDF) patches are laminated on the non-reflective side of the membrane mirror to serve as in-plane actuators. A new mathematical model of the piezoelectric actuated membrane mirror in multiple fields,(i.e., thermal,mechanical, and electrical field) is established, with which dynamic and static behaviors of the mirror can be analyzed.A closed-loop membrane mirror shape control system is set up and a surface shape control method based on an influence function matrix of the mirror is then investigated. Several experiments including surface displacement tracking and thermal deformation alleviation are performed. The deviations range from 15 μm to 20 μm are eliminated within 0.1 s and the residual deformation is controlled to micron level, which demonstrates the effectiveness of the proposed membrane shape control strategy and shows a satisfactory real-time performance. The proposed research provides a technological support and instruction for shape control of optical membrane mirrors.

Improvement on strip flatness of cold temper mills by modifying roll contour shape

A study on roll gap profile (strip profile) control was accomplished in a1700 mm single-stand temper mill. Some critical problems such as the deviation of work roll contourcaused by grinding and wear, the effectiveness of work roll bending were discussed. Using a finiteelement model, the effects of roll contours (ground and wear) on strip profile were investigated.The roll bending effect on strip thickness was also analyzed. It is pointed out that there are somespecial features of flatness control in the temper mill: during temper rolling, roll deformation isslight due to small rolling load, and the loaded roll gap profile mainly depends on work rollcontour, while the backup roll has a little effect on gap crown; the effect of bending force ongauge can not be ignored due to the coupling between flatness control and gauge control. A new rollcontour arrangement adaptable to the mill was presented and has been put into practical production.The application of the new set of rolls showed some good results: larger crown control range of workroll bender, higher rolling stability, better strip profile and flatness quality.

Shape control on probability density function in stochastic systems

A novel strategy of probability density function （PDF） shape control is proposed in stochastic systems. The control er is designed whose parameters are optimal y obtained through the improved particle swarm optimization algorithm. The parameters of the control er are viewed as the space position of a particle in particle swarm optimization algorithm and updated continual y until the control er makes the PDF of the state variable as close as possible to the expected PDF. The proposed PDF shape control technique is compared with the equivalent linearization technique through simulation experiments. The results show the superiority and the effectiveness of the proposed method. The control er is excellent in making the state PDF fol ow the expected PDF and has the very smal error between the state PDF and the expected PDF, solving the control problem of the PDF shape in stochastic systems effectively.

Finite element analysis of shape control for continuous hot rolling mills of super wide strip steel

The efficacy of shape control is the core of this technology and the main basis of automatic shape control system model designing. This passage constructs the three-dimensional elastic deformation model of CVCplus roll system in 2250 mm hot rolling mill. Comparing and analyzing different influence of working factors on control characteristic, the shape control characteristic of CVCplus roll system in its whole work time is studied, and the cause is analyzed and the difference of the roll gap curve and crown adjustable area in early and latter work time is compared. The outcome has crucial meaning in both theory and production.

Magnetic Sensorless Control of Plasma Position and Shape in a Tokamak

Magnetic sensorless sensing and control experiments with the plasma horizontal position have been carried out in the superconducting tokamak HT-7. The sensing is made to focus on the ripple frequency component of the power supply with thyristor and directly from them without time integration. There is no drift problem with the integrator of wagnetic sensors. Two kinds of control experiments have been carried out： to keep the position constant and swing the position in a triangular waveform, And magnetic sensorless sensing of plasma shape is discussed.

Static shape control of a flat shell structure

The eight-node and forty-DOF piezoelectric shell element were applied to shape control of a flat shell structure. By the direct and converse effects, a distributed piezoelectric sensor layer was used to monitor the shape deformation and a distributed actuator layer was used to suppresse the deflection. A finite element model was for static response of laminated shell with piezoelectric sensors/actuators was derived. The model was verified by calculating piezoelectric polymeric PVDF bimorph beam. The results are in good agreement with those obtained by theoretical analysis of Tzou and Hwang . A case study of the static shape control of a flat shell structure is presented.

Shape Control,Crystalline Conversion and Pseudocapacitance Properties of Mn3O4:Effects of Yb3+Doping

We report a facile method for the synthesis of manganese oxide（Mn3O4） nanorods via the direct reaction of MnCl2 and H2 O2 by doping Yb3＋ ions at room temperature and air atmosphere. The Mn3O4：Yb3＋ samples were characterized by X-ray diffraction（XRD）, scanning electron microscopy（SEM）, cyclic voltammetry（CVs）, electrochemical impedance spectroscopy（EIS）, and charging-discharging test（CD）. The results show that trace Yb3＋ doping（6 at%） could effectively induce crystalline transformation of Mn3O4 from cubic system（space group Fd-3 m） to tetragonal system（space group I41/amd） and incite the morphology changing from irregular particles to uniform nanorods. When Yb3＋ doping amount is 3%, the capacitance of Mn3O4 reaches the maximum, 246 F/g, which is related to the morphology change and the corresponding decrease of impedance.

Shape Control and Vibration Analysis of Pi-ezolaminated Plates Subjected to Electro-Mechanical Loading

Shape control and free vibration analysis of piezolaminated plates subjected to electro mechanical loading are evaluated using finite element method. First order shear deformation theory is employed in the analysis. Both extensions as well as shear actuators are considered for piezolaminated plates. Rectangular four node isoparametric element is used in the finite element formulation. Variation of temperature is neglected for the orthotropic layers of the laminate and for piezolayer. Annular circular plates and rectangular plates with piezoelectric layers mounted and/or integrated are analysed for various parameters. Numerical results are presented for varying the actuator voltage for annular plates with different thicknesses of piezo patches. In case of rectangular plate shear actuator is considered for vibration analysis.

STATIC SHAPE CONTROL OF LAMINATED PLATE CONTAINING PIEZOELECTRIC PATCHES

By applying the Heaviside function, the equations governinglaminated plates possess- ing spatially distributed piezoelectricpatches have been established. Based on these equations, static shapecontrol of laminated plates is discussed. BY using a genetic andcollocation algorithm, the opti- mal locations and scales of thesepiezoelectric patches have been selected. Numerical examples are pre-sented to illustrate the efficiency of the algorithm and thepiezoelectric actuators.

Shape Control and Modification of Rational Cubic B-Spline Curves

This paper considers the construction of a rational cubic B-spline curve that willinterpolate a sequence of data points x'+ith specified tangent directions at those points. It is emphasisedthat the constraints are purely geometrical and that the pararnetric tangent magnitudes are notassigned as in many' curl'e manipulation methods. The knot vector is fixed and the unknowns are thecontrol points and x'eightsf in this respect the technique is fundamentally different from otherswhere knot insertion is allowed.First. the theoretical result3 for the uniform rational cubic B-spline are presented. Then. in theplanar case. the effect of changes to the tangent at a single point and the acceptable bounds for thechange are established so that all the weights and tangent magnitUdes remain positive. Finally, aninteractive procedure for controlling the shape of a planar rational cubic B-spline curve is presented.

A new type of the generalized Bézier curves

In this paper, we improve the generalized Bernstein basis functions introduced by Han, et al. The new basis functions not only inherit the most properties of the classical Bernstein basis functions, but also reserve the shape parameters that are similar to the shape parameters of the generalized Bernstein basis functions. The degree elevation algorithm and the conversion formulae between the new basis functions and the classical Bernstein basis functions are obtained. Also the new Q-Bezier curve and surface constructed by the new basis functions are given and their properties are discussed.

A novel induction motor control scheme using IDA-PBC

A new control scheme for induction motors is proposed in the present paper, applying the interconnection and damping assignment-passivity based control （IDA-PBC） method. The scheme is based exclusively on passivity based control, without restricting the input frequency as it is done in field oriented control （FOC）. A port-controlled Hamiltonian （PCH） model of the induction motor is deduced to make the interconnection and damping of energy explicit on the scheme. The proposed controller is validated under computational simulations and experimental tests using an inverter prototype.

Comprehensive contour prediction model of work rolls in hot wide strip mill

The predictive calculation of comprehensive contour of work rolls in the on-line strip shape control model during hot rolling consists of two important parts of wear contour calculation and thermal contour calculation, which have a direct influence on the ac- curacy of shape control. A statistical wear model and a finite difference thermal contour model of work rolls were described. The comprehensive contour is the equivalence treatment of the sum of grinding, wear, and thermal contours. This comprehensive contour calculation model has been applied successfully in the real on-line strip shape control model. Its high precision has been proved through the large amounts of actual roll profile measurements and theoretical analyses. The hit rates （percent of shape index satisfying re- quirement） of crown and head flatness of the strips rolled, by using the shape control model, which includes the comprehensive contour calculation model, have about 16% and 10% increase respectively, compared to those of strips rolled by using manual operation.

Triply periodic minimal surface(TPMS)porous structures:from multi-scale design,precise additive manufacturing to multidisciplinary applications

Inspired by natural porous architectures,numerous attempts have been made to generate porous structures.Owing to the smooth surfaces,highly interconnected porous architectures,and mathematical controllable geometry features,triply periodic minimal surface(TPMS)is emerging as an outstanding solution to constructing porous structures in recent years.However,many advantages of TPMS are not fully utilized in current research.Critical problems of the process from design,manufacturing to applications need further systematic and integrated discussions.In this work,a comprehensive overview of TPMS porous structures is provided.In order to generate the digital models of TPMS,the geometry design algorithms and performance control strategies are introduced according to diverse requirements.Based on that,precise additive manufacturing methods are summarized for fabricating physical TPMS products.Furthermore,actual multidisciplinary applications are presented to clarify the advantages and further potential of TPMS porous structures.Eventually,the existing problems and further research outlooks are discussed.