Vibratory Mill Research Articles

Robust low-complexity vibration suppression control of rolling mill with time-varying state constraints

In this paper, a novel robust low-complexity vibration suppression control scheme is proposed for the vertical-torsional-horizontal coupling vibration of the rolling mill. To facilitate the control design, the overall coupling vibration system is decoupled into vertical-horizontal coupling vibration subsystem and torsional vibration subsystem. For the vertical-horizontal coupling vibration subsystem, a novel robust low-complexity controller is designed via constructed error transformations to provide strong robustness against uncertainties and disturbances. For the torsional vibration subsystem, a new robust state feedback controller is constructed via a backstepping technique to ensure the vibration angle of the motor rotor within given constraints via a proper asymmetric barrier function. The overall coupling vibration system is proved to be stable in the sense of uniform ultimate boundedness, and the vibration amplitude of the rolling mill can be reached arbitrarily small by selecting appropriate controller parameters. The numerical simulation is performed to verify the effectiveness and the superiority of the proposed control strategy.

A novel mechanocatalytic process by vibratory disk mill for efficient hydrolysis of cellulose, chitin and xylan

Polysaccharides are primary sources to manufacture chemical products with low carbon footprints, owing to their carbons from atmospheric carbon dioxide fixed through photosynthesis. Breaking down such polysaccharides into water-soluble saccharides through the hydrolysis of glycosidic bonds is one of key steps to produce valuable chemicals; however, previous chemical and enzymatic processes have been suffered from their fundamental drawbacks (e.g. not environmentally benign, high production cost) and are not regarded as feasible approaches. Recently, mechanocatalytic process, which proceeds hydrolysis of polysaccharides by simply milling with solid acids, attracts attentions owing to its cost-effectiveness and environmental beingness. Herein, we propose the novel mechanocatalytic system to efficiently proceed the hydrolysis of glycosidic bonds in polysaccharides by using “vibratory disk mill”, which can produce strong shear and impact force. By milling polysaccharides (cellulose, chitin and xylan) with solid acid kaolin, the polysaccharides can be efficiently hydrolysed to water-soluble saccharides with a rate twice higher than the previous milling devices, achieving quantitative conversion of polysaccharide to water soluble products (solubility: >99 %). We elucidated the reaction mechanism of polysaccharides with kaolin by X-ray diffractograms: forces produced by the vibratory disk mill can efficiently delaminate layered aluminosilicate nanosheets in kaolin, leading to better accessibility of polysaccharides on the acidic surface of the nanosheets. This novel mechanocatalytic system can also be applicable to produce oligosaccharides directly from crude biomass samples (birchwood chips and shrimp shells) without any chemical purification steps, demonstrating that this system can be used in industrial biomass processing.

Prediction of vibration in milling of thin-walled aluminum alloy parts using neural network model

Machining chatter is likely to occur during milling of thin-walled parts. The structural differences in thin-walled parts and the magnitude of the milling force can lead to varying degrees of chatter in different areas of the machining process. Predicting machining stability using dynamic modeling methods can be time-consuming. In this study, a method for establishing a particle swarm optimization-back propagation (PSO-BP) neural network model is proposed to predict the modal parameters of thin-walled parts and the surface vibration of machined parts. Based on measurements of the length, height, wall thickness, and position of the thin-walled parts, the modal parameters of the workpiece were predicted using the PSO-BP neural network model. Additionally, the average milling force was included as an input parameter to predict the displacement of surface vibrations on thin-walled parts using the PSO-BP model. The predictive results of the modal parameters and surface vibration displacement are evaluated using the evaluation function, which indicates that the PSO-BP neural network model can reliably predict the modal parameters and surface vibration depth of thin-walled parts.

Study on vertical-torsional chatter under asymmetric conditions in tandem cold rolling

The vibrations generated by the rolling mills significantly impair the production quality and efficiency of cold tandem rolling. Considering that the main drive system constitutes one of the energy sources of vibration, this study integrates the vertical structure of the rolling mill with the torsional structure of the main drive system for a comprehensive analysis. This study establishes an asymmetric dynamic rolling force model that accounts for the structural asymmetry of the rolling mill, the asymmetric power transmission between the upper and lower connecting shafts of the main drive system, and the long-term wear and friction conditions of the mechanical equipment. Furthermore, this study accounts for the speed differential between the upper and lower work rolls induced by torsional vibrations. Based on these interdependent parameters, this study develops a rolling mill vibration coupling model to comprehensively assess stability. The validation of the model confirms its high accuracy. Variations in rolling torque under different roll speed ratios, friction coefficient ratios, and roll diameter ratios were analyzed, along with the impact of the cross-shear zone's proportion on system stability under key rolling parameters. Furthermore, changes in rolling torque, amplitude, and the cross-shear zone during unstable operating conditions were examined. Finally, the interaction between the vertical and torsional structures was studied, providing a theoretical foundation for optimizing process parameters and mitigating vibrations in the continuous cold rolling process.

Modeling of cutting force and tool vibration in helical milling using mechanistic models and artificial neural network

Modeling of cutting force and tool vibration in helical milling using mechanistic models and artificial neural network

Controlling harmful milling vibration for robotic milling system based on the optimization of milling posture and spindle speed

Harmful machining vibration including milling chatter and resonance are easily generated during robotic milling process, and it seriously restrict the machining ability of the robot. To address this problem, a harmful machining vibration-controlled method based on the combined optimization of milling posture and spindle speed is proposed for robotic milling system in this paper. With this context, firstly, the robot stiffness model is established based on the theory of the multi-body with small-deformation, and the stiffness ellipsoid at the tool cutting point is used to optimize the milling posture, so that the structure stiffness of the robot can be enhanced; Then, the robot chatter stability model is constructed considering the modal coupling effect, and the spindle speed is optimized to restrain the milling chatter and resonance. Finally, with the optimized milling posture and spindle speed, the milling process is planned and performed with a Staubli TX-200 robot, and two experiments for workpiece with steel and aluminum are implemented to verify the proposed method. The experiment results demonstrate that the comprehensive optimization of milling posture and spindle speed can efficiently control the harmful machining vibration for the robotic milling system, thus, the machining quality of the workpiece can be improved.

Model of Dynamic Mechanical Parameters and Vibration Analysis in Hot Rolling

As the core equipment of metal shaping processing, the vibration problem of rolling mill seriously affects the product quality and production efficiency. To address the problem of the limited prediction of mill vibration due to small sample data in non-steady states, we propose to predict dynamic mechanical parameters (rolling force and rolling torque) based on the TCN-LSTM step strategy transfer model. The prediction accuracies of the TCN-LSTM step strategy transfer model under 1000 sets of training data reach 95.8% and 93.2%, respectively, and at the same time, it saves the time of training and regulation of the deep learning model and can better meet the needs of online prediction. The horizontal-torsion hot rolling vibration model is further established to quantitatively analyze the relationship between process parameters and mill vibration. The experimental results show that with the vibration suppression measures of 10% reduction of the rolling speed and 10% reduction of the entrance thickness, the horizontal vibration displacement amplitude is reduced from 0.687 × 10−4 m to 0.229 × 10−4 m, and the rotational displacement amplitude is reduced from 0.0273 m to 0.0117 m, which effectively suppresses the vibration of the mill and improves the stability of the rolling process.

DISPERSED POLYOXADIAZOLE MODIFIER FOR ANTIFRICTION PHENOLFORMALDEHYDE TEXTOLITES

Antifriction polymer composite materials based on phenol-formaldehyde resole binders, reinforced with textile-combined polyoxadiazole and cellulose fibers, have high tribological and physical-mechanical properties. This opens up prospects for solving a wide range of problems in the design of friction units of machines and mechanisms with an extended service life. However, when processing these materials into finished products, technological difficulties arise that limit their use. The use of a dispersed modifier simplifies the technology for producing polymer composite materials. By grinding polyoxadiazole fibers in a ball vibration mill, a new type of anti-friction dispersed modifier of phenol-formaldehyde binders was obtained. In accordance with the data of diffractometric analysis, when grinding polyoxadiazole fiber, there is a slight decrease in its crystallinity, which has virtually no effect on the physical and mechanical properties of the material. The resulting dispersed modifier is a mixture of short fragments of deformed polyoxadiazole filaments and flaky polyoxadiazole particles of irregular shape, the size of which reaches 200-250 µm. X-ray photoelectron spectroscopy data indicate an increase in the nitrogen content in the resulting powdered product compared to the original polyoxadiazole fiber. The introduction of a powdered polyoxadiazole modifier into a phenol-formaldehyde binder for cotton textolites ensured the production of self-lubricating wear-resistant antifriction polymer composite materials with good tribological properties. A decrease in the coefficient of friction, wear and temperature in the friction contact zone is observed (under conditions of dry friction on a steel counterbody). The samples of the studied materials with a small content of polyoxadiazole modifier (5% wt.) in the phenol-formaldehyde binder have the best tribological characteristics. The properties of the resulting materials are due to polymer composite materials reinforced with a fabric combination of fibers, polyoxadiazole and cellulose. For citation: Panova M.O., Buyaev D.I., Shaposhnikova V.V. Dispersed polyoxadiazole modifier for antifriction phenolformaldehyde textolites. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 11. P. 79-85. DOI: 10.6060/ivkkt.20246711.7051.

Synthesis of core-functionalised naphthalene diimides from naphthalenetetracarboxylic dianhydride using a vibratory ball mill: bromination, imidization and Heck-type reactions.

The synthesis of 9 core-functionalised naphthalene diimide (c-NDI) residues is reported via a 3-step solvent free synthesis from naphthalenetetracarboxylic dianhydride using only mechanochemical activation. Selective dibromination and subsequent dimidiation were achieved for the first time in a vibratory ball mill, resulting in the key structural intermediate, 2,6-dibromonaphthalenediimide (DBND), which is the basis for elaboration into a multitude of organic electronic materials. Our new synthesis of DBND is achieved in just 5 hours' reaction time over two steps compared to typical solution state times of 24 hours. Subsequent Heck-type cross coupling reactions, with a range of styrene residues, produced a series of c-NDIs in good yields. The Heck-type reactions are rapid (1.5 hours), require no additional heating or solvent and are tolerant of atmospheric moisture and air.

Investigating the Surface Quality of Aramid Honeycomb Materials Through Longitudinal–Torsional Ultrasonic Milling

During the milling process of aramid honeycomb, residual stresses arise, which will affect the surface quality of the honeycomb. Studies have shown that reasonable processing techniques can reduce residual stresses, indicating a close relationship between residual processing stresses and the processing parameters, such as technique. By investigating the changes in residual stresses after the processing of aramid honeycomb materials, the influence of processing techniques on these changes is analyzed. Leveraging the correlation between residual stresses and surface quality, this study proposes the use of residual stress as an indicator for evaluating processing techniques. The longitudinal–torsional ultrasonic vibration milling method is applied to the processing of aramid honeycombs. A single-factor experimental approach is adopted, utilizing ABAQUS 2020 software to mimic the longitudinal–torsional ultrasonic milling process. This study explores the influence patterns of various process parameters on the residual stresses generated during the milling of honeycombs. The simulation results indicate that within the selected range, the residual stress decreases as the tool rotation speed increases, while it increases with the increase in feed rate. The influence of milling depth on residual stress can be negligible. Furthermore, experiments were conducted based on the proposed correlation between residual stress and surface quality. The experimental results show good agreement with the simulation results, indicating that under reasonable process parameters, the residual stress values decrease, thereby improving the milling surface quality of aramid honeycomb materials. Therefore, measuring residual stress can serve as an effective method for evaluating the processing technique.

A process parameters decision approach considering spindle vibration in helical surface milling for minimising energy consumption and surface roughness value

A process parameters decision approach considering spindle vibration in helical surface milling for minimising energy consumption and surface roughness value

Analyzing the correlation between tool vibration and flank wear in face milling of EN-31 steel employing the CRITIC approach

Analyzing the correlation between tool vibration and flank wear in face milling of EN-31 steel employing the CRITIC approach

Operational Modal Analysis of Self-excited Vibrations in Milling Considering Periodic Dynamics

Abstract A new method is presented to identify the dynamics of regenerative chatter from measured process vibrations in milling. This method combines the synchronous once-per-revolution sampling of process vibrations with Operational Modal Analysis to estimate the Floquet multipliers of the delayed linear time-periodic dynamics in milling, all from the natural process vibrations without external excitation. The identified multipliers quantify vibration stability, enabling chatter prediction before it occurs. In addition to this, they can be used to calibrate physics-based chatter models based on vibration measurements solely within the stable region. The method's accuracy in identifying Floquet multipliers is validated through extensive numerical simulations and two experimental case studies. The results show that chatter due to both Hopf and period-doubling bifurcations can be predicted from the process vibrations during stable cuts. Moreover, the experimental case studies demonstrate a vibration measurement system for implementing the presented method in standard milling operations and confirm its effectiveness in practice.

Longitudinal torsional ultrasonic vibratory assistant milling of borosilicate glass material removal mechanism based on the thickness of undeformed chips

Borosilicate glass is an ideal material for microfluidic chip substrates due to its excellent light transmittance and stable chemical properties. However, it is also prone to brittle fracture during processing, making it a typical difficult-to-machine material. As an emerging processing technology, longitudinal torsional ultrasonic assistant milling (LTUVAM) can effectively reduce the surface damage of glass materials and improve the proportion of plastic removal of materials. The mechanism of LTUVAM of borosilicate glass was studied in this paper. Critical undeformed chip thickness (hc) is a key factor in achieving plastic material removal. At present, the influence of LTUVAM on the hc is not clear. Therefore, in this paper, the material-specific cutting energy model in the LTUVAM process was established to predict the hc. Firstly, the motion path of LTUVAM was analyzed, and the undeformed chip thickness model and the tool-workpiece separation rate model were established. Then, based on the above model, the material-specific cutting energy model was established according to the material removal principle. Finally, an LTUVAM orthogonal experiment was carried out to study the surface quality of the material. The experimental results showed that with the increase of ultrasonic power, the roughness and side damage area increased first and then decreased. With the increase of spindle speed, it showed that the roughness and side damage area decreased first and then increased. With the increase of feed per tooth, it showed that the roughness increased first and then decreased, and then increased, and the side damage area increased first and then decreased. Through the analysis of the experimental and model results, the increase of the separation rate between the tool and the workpiece contributes to the increase of the hc and the improvement of the processing quality.

Mechanism of tetracycline sorption on carbon-bentonite

Antibiotics increased industrial production is the reason of their occurrence in wastewater, soils, groundwater, and drinking water. In this regard, treating the environment for pharmaceuticals is one of the urgent environmental challenges. Synthesis of adsorbents using different types of raw materials by the methods of mechanochemical activation makes it possible to significantly increase their sorption capacity due to the accumulation of various kinds of defects in the crystal structure of the adsorbent. We obtained the bentonite-carbon composite using roller-ring vibratory mill with coal-bentonite ratio of 30 : 70 and 50 : 50. However, the nature of the interaction between carbon and bentonite correlates with changes of surface area and porosity. The porous structure parameters of the samples show the mechanochemical activation of the mixture involves their components interactions. The authors studied the structural and chemical changes during the modification of bentonite with activated carbon by analysing the vibrational spectra of carbon, initial, and modified aluminosilicate samples. According to infrared spectroscopy of adsorbents, absorption bands characteristic of Si-O-C bond vibrations occurred. The paper investigates the sorption capacity of mechanochemically modified natural clay mineral Dash-Salakhli bentonite towards tetracycline hydrochloride. Research investigates the kinetics of the process and rapid sorption of tetracycline. The paper provides possible mechanisms of chemisorption due to donor-acceptor interaction and ion-exchange processes.

Transmission and Dissipation of Vibration in a Dynamic Vibration Absorber-Roller System Based on Particle Damping Technology

The research of rolling mill vibration theory has always been a scientific problem in the field of rolling forming, which is very important to the quality of sheet metal and the stable operation of equipment. The essence of rolling mill vibration is the transfer of energy, which is generated from inside and outside. Based on particle damping technology, a dynamic vibration absorber (DVA) is proposed to control the vertical vibration of roll in the rolling process from the point of energy transfer and dissipation. A nonlinear vibration equation for the DVA-roller system is solved by the incremental harmonic balance method. Based on the obtained solutions, the effects of the basic parameters of the DVA on the properties of vibration transmission are investigated by using the power flow method, which provides theoretical guidance for the selection of the basic parameters of the DVA. Furthermore, the influence of the parameters of the particles on the overall dissipation of energy of the particle group is analyzed in a more systematic way, which provides a reference for the selection of the material and diameter and other parameters of the particles in the practical application of the DVA. The effect of particle parameters on roll amplitude inhibition is studied by experiments. The experimental results agree with the theoretical analysis, which proves the correctness of the theoretical analysis and the feasibility of the particle damping absorber. This research proposes a particle damping absorber to absorb and dissipate the energy transfer in rolling process, which provides a new idea for nonlinear dynamic analysis and stability control of rolling mills, and has important guiding significance for practical production.

Study on the processing performance of 60% SiCp/Al composite materials assisted by longitudinal and torsional ultrasonic vibration milling

Study on the processing performance of 60% SiCp/Al composite materials assisted by longitudinal and torsional ultrasonic vibration milling

Experimental study of wet and dry milling effect on surface roughness of TC4 titanium alloy

Titanium alloys are important engineering materials used in various industry areas, such as aviation, aerospace and medical devices. The surface roughness is a significant parameter for assessing the machining quality of titanium alloys. In this study, in order to compare the effects of dry and wet milling conditions on the surface roughness of titanium alloys, we established a test system to obtain the surface roughness, three-dimensional milling vibration and three-dimensional milling force signals. The gray correlation theory was applied to investigate the correlation between surface roughness and milling vibration or milling force under dry and wet milling conditions. Using the least squares method, the prediction models of surface roughness corresponding to dry and wet milling conditions were developed according to the features of vibration or force signals. Furthermore, the combined prediction models of surface roughness that integrate multiple signal features and milling parameters were established. The comparison results revealed that there was a stronger correlation between roughness and milling force, milling vibration in wet milling. Wet milling exhibited significantly lower roughness compared to dry milling under the same machining parameters, with up to a 59% reduction. The correlation coefficient of the wet milling model is as high as 0.95.

Optimization of Tool Wear and Cutting Parameters in SCCO2-MQL Ultrasonic Vibration Milling of SiCp/Al Composites

Silicon carbide particle-reinforced aluminum matrix (SiCp/Al) composites are significant lightweight metal matrix composites extensively utilized in precision instruments and aerospace sectors. Nevertheless, the inclusion of rigid SiC particles exacerbates tool wear in mechanical machining, resulting in a decline in the quality of surface finishes. This work undertakes a comprehensive investigation into the problem of tool wear in SiCp/Al composite materials throughout the machining process. Initially, a comprehensive investigation was conducted to analyze the effects of cutting velocity vc, feed per tooth fz, milling depth ap, and milling width ae on tool wear during high-speed milling under SCCO2-MQL (Supercritical Carbon Dioxide Minimum Quantity Lubrication) ultrasonic vibration conditions. The results show that under the condition of SCCO2-MQL ultrasonic vibration, proper control of milling parameters can significantly reduce tool wear, extend tool service life, improve machining quality, and effectively reduce blade breakage and spalling damage to the tool, reduce abrasive wear and adhesive wear, and thus significantly improve the durability of the tool. Furthermore, a prediction model for tool wear was developed by employing the orthogonal test method and multiple linear regression. The model’s relevance and accuracy were confirmed using F-tests and t-tests. The results show that the model can effectively predict tool wear, among which cutting velocity vc and feed rate fz are the key parameters affecting the prediction accuracy. Finally, a genetic algorithm was used to optimize the milling parameters, and the optimal parameter combination (vc = 60.00 m/min, fz = 0.08 mm/z, ap = 0.20 mm) was determined, and the optimized milling parameters were tested. Empirical findings suggest that the careful selection of milling parameters can significantly mitigate tool wear, extend the lifespan of the tool, and enhance the quality of the surface. This work serves as a significant point of reference for the processing of SiCp/Al composite materials.

Vertical vibration analysis of rolling interface based on dynamic rolling force with variable friction characteristics

This study investigates the impact of variable friction characteristics at the rolling interface on the vertical vibration of plate and strip rolling mills. Based on the optimized Karman equilibrium theory, a dynamic rolling force model considering the front and back tension, elastic stretching, and rolling speed was established. The amplitude-frequency response equation of rolling mill system is solved by multi-scale method, and the influence of main parameters on vertical vibration of rolling mill system is analyzed. The results show that the increase of the first stiffness coefficient of dynamic rolling force leads to the decrease of the principal common amplitude of the system. On the contrary, when the third stiffness coefficient increases, the system exhibits a jump phenomenon. When the third stiffness coefficient of dynamic rolling force is reduced within a certain range, a stable and unique solution is obtained without jumping phenomenon. Moreover, the smaller the damping coefficient of the upper and lower roller system is, the larger the vibration amplitude is and the jump phenomenon occurs. Decreasing the external disturbance force can effectively reduce the system’s vertical vibration amplitude and suppress the resonance. In addition, with the change of external disturbance force, the roll system of the rolling mill shows a variety of complex motion states, such as periodic motion, double-periodic motion, and chaotic motion. The research results provide an effective theoretical reference for the suppression of vertical vibration of rolling mill.