Vibratory Mill Research Articles

Study on the effect of rolling mill dynamic stiffness on coupled vibration of hydraulic machine

The productivity and capacity release of hot-strip rolling is severely limited by pendular vibration. Previous studies on mill vibration have investigated the influence of rolling parameters on vertical vibration; however, the influence of dynamic stiffness compensation factors on vertical vibration has not yet been considered owing to the limitations of modelling methods. Herein, we develop a simulation model of mill liquid–machine coupling with dynamic stiffness compensation using AMESim software. The established simulation model is used to investigate the effect of this dynamic stiffness compensation on mill vertical vibration under conditions of downfeed thickness difference excitation frequency, thickness difference excitation amplitude, thickness difference excitation phase, and dynamic stiffness compensation signal generation hysteresis. Evidently, the impact of the mill stiffness compensation on the mill vertical vibration differs with the thickness of the excitation frequency, and the impact should be discussed according to the excitation frequency segment. The amplitudes of the roll system vibration and incoming thickness difference excitation are essentially linear, whereas the excitation phase does not affect the frequency or amplitude of the mill vibration. The rolling machine stiffness compensation signal hysteresis also has a significant impact on the mill vibration amplitude. Our findings will improve the mechanism of the hot rolling process and suppress droop vibrations.

Suppression of cutting vibration in side milling of laser cladded layer on thin-walled parts with interfacial structures

Laser cladding is being employed for repairing high-end components including thin-walled parts. The heterogeneous interface between cladding layer and substrate can exacerbate cutting vibration during subsequent machining, becoming a bottleneck in remanufacturing thin-walled parts. This paper focuses on exploring the effect of interfacial structures on cutting vibration suppression in side milling of laser cladded layer on thin-walled parts. First, the interfacial structure was proven to be effective for suppressing cutting vibration by increasing modal damping, although the stiffness shows a decreasing trend. Among different interfacial structures, triangular structure showed the best role in cutting vibration suppression, followed by rectangular, semi-circular, and trapezoid. Then, the effects of different structural parameters on cutting vibration suppression were further analyzed based on a Taguchi design. The results showed that the cutting vibration decreases with the smaller interfacial shape factor, larger depth and smaller spacing of interfacial structures. The interfacial structure would be optimal when the interfacial shape factor is 0.06, the interfacial depth is 3.0 mm, and the spacing is 0 mm. As a result, the cutting vibration during milling was reduced by 55.28 %. These findings provide a theoretical basis for high-quality remanufacturing of the thin-walled parts.

Thermodynamic limits of the depolymerization of poly(olefin)s using mechanochemistry.

Mechanochemistry is a promising approach for chemical recycling of commodity plastics, and in some cases depolymerization to the monomer(s) has been reported. However, while poly(olefin)s comprise the largest share of global commodity plastics, mechanochemical depolymerization of these polymers in standard laboratory-scale ball mill reactors suffers from slow rates. In this work, the observed reactivities of poly(styrene), poly(ethylene) and poly(propylene) are rationalized on the basis of thermodynamic limitations of their depolymerization by depropagation of free radical intermediates. In addition, subsequent phase partitioning equilibria for the removal of monomers from the reactor via a purge gas stream are discussed for these polymers. For poly(styrene), a typical vibratory ball mill supplies just enough energy for its depolymerization to be driven by either thermal hotspots or adiabatic compression of the impact site, but the same energy supply is far from sufficient for poly(propylene) and poly(ethylene). Meanwhile, removal of styrene from the reactor is thermodynamically hindered by its lower volatility, but this is not an issue for either propylene or ethylene. The implications of these thermodynamic limitations for mechanochemical reactor design and potential for mechanocatalytic processes are highlighted.

Evaluation the Effectiveness of the Comminution Process in a New Rotary Vibration Mill Using the Finite Element Method

With the rapid development of nanotechnology the urgency of the issue of increasing the efficiency of fine and ultrafine comminution of materials has increased. Nowadays, one of the most popular issues is to obtain a grinding product with a size of less than 20 μm for various technological processes. The purpose of the investigations presented in this paper is an increasing in the effectiveness of fine and ultrafine grinding process. To achieve this purpose, the authors of the article have analyzed new technical solutions to improve the efficiency of fine and ultrafine comminution. Based on the existing principles for improving the design of stirred mills, a new design of the so-called «rotor-vibratory mill» has been proposed. Using the finite element method, the efficiency of the proposed design of the mill with the support of computer simulation of the grinding process has been evaluated. The results of the investigations showed that the new design of the mill allows to increase the product fineness by 69...75% and decrease the time of the grinding process by 60...74% in comparison with existing analogues.

Water Solubilization and Guest Molecule-Induced Fluorescence Changes of Porous Host Molecules via Complexing with Polysaccharide or Polypeptide.

To detect small aromatic molecules in water, we prepared functional host molecules based on water-soluble N,N'-bis(2-aminobenzophenone)-1,4,5,8-naphthalenetetracarboxylic diimide (1) and a solubilizing agent using a high-speed vibration milling apparatus. The fluorescence response of host 1-solubilizing agent complexes before and after extraction of small aromatic guest molecules was large and the fluorescence maxima were dependent on the small aromatic guest molecules.

Exploration of surface milling machining process of C/SiC composites based on quality improvement

C/SiC composites have the advantages of high strength, oxidation resistance and high temperature resistance, which are widely used in aerospace high temperature structures. However, the machining apparent quality has also become an important factor limiting its application. Therefore, this paper investigates the effects of cutting force, tool parameters and tool wear on the apparent quality of ultrasonic vibration milling of C/SiC composites. And the effect of tool selection and tool path on the milling surface roughness of C/SiC compliant materials is proved by experiments. In order to provide certain reference for the improvement of the surface milling quality of C/SiC composite materials.

Scalability of Pharmaceutical Co-Crystal Formation by Mechanochemistry in Batch.

The development of mechanochemistry is considerably growing. Benign by design, this technology complies with several principles of green chemistry, contributing to the achievement of the United Nations Sustainable Development Goals (UN SDGs) and the European Green Deal objectives. Herein, we report the use of mechanochemical processes in batch to prepare kilogram-scale of the Active Pharmaceutical Ingredient (API): Ibuprofen-Nicotinamide (rac-IBP:NCT) co-crystal in an industrial eccentric vibration mill. This scenario shows a sustainable approach to the industrial up-scaling of pharmaceutical co-crystals by a solvent-free mechanochemical process in batch. The quantitative assessment of the greenness of the mechanochemical process against the Twelve Principles of Green Chemistry was performed using the DOZN 2.0 Green Chemistry Evaluator.

Pose-dependent natural frequency prediction for milling robot—A variable joint stiffness model

Low prediction accuracy of natural frequencies of a milling robot is one major obstacle to the avoidance of chatter vibration in low-speed robotic milling. For enhanced accuracy in predicting the natural frequency of mixed robot, a variable stiffness model is proposed featuring the dependency of joint stiffness on the joint variables, rather than the constant joint stiffness in the traditional assumption. By integrating the variable joint stiffness model into a mode-reduced 4DOF model modified for the present study, the new method for predicting the robot natural frequency is then built, analyzed, and verified through simulation and modal tests by both a 3-axis accelerometer and a laser vibrometer on the milling robot under different robot configurations. Comparison of the experimental values from the modal tests against the natural frequencies predicted by the proposed model reveals a predicting error of less than 10%, hence enhanced accuracy of the proposed variable joint stiffness model in a large operational space. Based on the model, milling parameters without structural vibration has been selected, and the quality of the robot milling for titanium alloy has been improved.

Vertical nonlinear vibration analysis of cold rolling mill considering structural gap and dynamic rolling force

To reveal the impact of vertical nonlinear vibration on the stabilization of the precision cold rolling system, the vertical nonlinear vibration model with consideration of structural gap and dynamic rolling force has been established. Utilizing the Magnus series method with high accuracy and long-term numerical stabilization, we calculate the vibration response of the cold rolling system and conduct numerical simulations to determine the bifurcation characteristics, maximum Lyapunov exponent, and two-parameter dynamical behavior. The results reveal the parameter regions of bifurcation and chaos that cause the vibration instability of the cold rolling system. It has also been found that the system has the nonlinear phenomenon of transition from period-3 motion to chaotic motion. More importantly, two-parameter matching regions for the cold rolling system performing periodic and chaotic motions are determined. Two-parameter matching solutions for improving and deteriorating the stabilization of the cold rolling system are clarified, and the preferred matching regions for the parameters coupling with the structural gap and dynamic rolling force are revealed. The results reveal the impact of system parameters upon the vertical nonlinear vibration of the cold rolling mill, which can serve as an academic reference for reducing the vibration and enhancing the stabilization of the cold rolling system.

Product contamination during mechanochemical synthesis of praziquantel co-crystal, polymeric dispersion and cyclodextrin complex

This paper aims to evaluate the product contamination by elemental impurities during the mechanochemical synthesis of praziquantel (PZQ) co-crystal, polymeric dispersion and cyclodextrin complex by grinding. To assess that, PZQ was co-ground with malic acid (MA), Poloxamer F-127 (F-127) and hydroxypropyl-β-cyclodextrin (HPβCD) in high-energy vibrational mills using stainless steel and agate grinding tools, applying different processing time (30 and 90 min). Differential scanning calorimetry and X-ray powder diffraction confirmed the formation of the targeted products, regardless of applied processing time and grinding tool type. After digestion of the solid powder products, the levels of selected elemental impurities were analysed by inductively coupled plasma mass spectrometry (ICP-MS). The analysis revealed that the content of Mg, Ca, and V are below the limit of quantification in all samples analysed. The contents of P and Na are not related to the type of ball mill and reaction time, but to the starting materials themselves, considering that Na is found in HPβCD and MA, while P was found in F-127. The detected Si impurities in the co-ground products can be related to the use of the agate balls and jars, while the presence of Cr and Fe can be related to the use of the stainless steel grinding tools. The risk assessment showed that the oral administration of the prepared co-ground products in quantities corresponding to regular PZQ oral doses resulted in only insignificant exposure to Cr. Finally, the use of agate grinding tools should be preferred, as administration of such products results in lower Cr exposure. The presented elemental impurities did not lead to any significant drug degradation as PZQ content at the end of the six-month testing period was still in the range of 95–105 % of the initial content. Regardless, ICP-MS analysis of the elemental impurities should be considered in regular quality control procedures in the development and production of novel pharmaceutical products prepared by grinding.

Achieving high strength-ductility in TiBw-GNPs/Ti6Al4V composites via 3D interface configuration

Strong interface bonding is critical to achieve the graphene nanoplates reinforced titanium matrix composites (GNPs/TMCs) with excellent strength and ductility. In this study, the TiBw-GNPs/Ti6Al4V composites with three-dimensional (3D) interface configuration are fabricated through the combination of vibration milling and the spark plasma sintering (SPS). The 3D interface configuration is constructed by the in-situ generated TiB whiskers (TiBw) together with the sandwiched TiC-GNPs-TiC, in which TiBw grow epitaxially into the adjacent Ti6Al4V grains and immobilize TiC-GNPs-TiC. As a result, 1.5 wt%TiBw-GNPs/Ti6Al4V composite exhibit simultaneously improved yield strength, ultimate strength and ductility, manifesting marked increments of 26.5%, 26.4% and 30.1% compared to GNPs/Ti6Al4V composite, respectively. The strengthening enhancement of TiBw-GNPs/Ti6Al4V composites can be mainly attributed to the constructed 3D interface microstructure, which boosts the interface bonding and promotes grain refinement as well as load transfer. Moreover, the equiaxed α-Ti phase and the deformation compatibility gifted from the tailored interface endow the TiBw-GNPs/Ti6Al4V composites with excellent ductility. This strategy of tailoring 3D interface configuration could pave a promising way to obtain robust interfacial bonding and break through the strength-ductility trade-off in graphene reinforced titanium matrix composites.

Investigation on active vibration control to improve surface quality in precision milling process

The tool-workpiece vibration in the precision milling process plays a pivotal role in influencing the surface quality. To solve the machining problem coming with the process vibration, the active vibration control model as well as the corresponding platform are developed, and the active vibration control algorithms are applied to reduce the relative vibrations and improve the surface quality. Firstly, the milling vibration reduction and surface quality improvement are modeled based on the active control algorithms and the system dynamic characteristics. Then, applying the different algorithm control strategies, such as PID, Fuzzy PID, BP neural network, and BP neural network PID control, the control effect is simulated and analyzed. Finally, an experimental platform is established to validate the system’s reliability. The efficiency of various active control methods is compared in terms of frequency vibration control and surface finish roughness improvement. The results indicate that under different milling parameters, the four algorithm control strategies exhibit optimal effects of 13.5%, 30.4%, 28.8%, and 40.1% respectively. These findings provide valuable insights into selecting the optimal vibration control method for precision milling.

Identification method for unsteady friction of tool flank for high efficiency milling cutter

Under the cutting loads of high efficiency and intermittent, the friction status between the tool flank and transition surface has time-varying characteristics, which directly affects friction and wear performance of the milling cutter. The dynamic distribution of instantaneous friction on tool flank under milling vibration needs to be revealed. In this work, the effect of milling vibration on instantaneous cutting contact relationship between milling cutter and workpiece was researched, a calculation method for the instantaneous friction velocity and friction energy consumption on tool flank was proposed. The variation of instantaneous friction between tool flank and transition surface under milling vibration was identified and evaluated by power spectral entropy and cross-correlation function. A method for identifying the unsteady friction of tool flank was proposed. The response analysis and experimental verification were conducted. The results showed that the frequency domain parameter distribution of friction energy consumption on tool flank had a strong correlation with the wear depth distribution, and was obviously sensitive to the milling parameters. The above models and methods could be used to reveal the influence of key milling process variables on unsteady friction and wear process of milling cutter’s multiple tool flank.

Interactive coupling of structural dynamics and milling forces for high-frequency stability prediction in robotic milling

Robotic machining has developed rapidly and has great potential for manufacturing large parts with complex surfaces. However, the machining quality and efficiency are severely limited by the low stiffness of the robots, which causes destructive chatter during manufacturing. To suppress this phenomenon, offline stability prediction must be performed before the actual robotic milling. In this study, a high-frequency stability prediction algorithm for robotic milling was developed by introducing an interactive method. A lightweight structural dynamic model of a robot was developed based on specially designed decoupling criteria, and an interpolation algorithm that determines the trajectory of the tool nose was designed to calculate the milling force. By combining the two models, an interactive coupling algorithm was proposed to forecast the vibration in robotic milling. The predicted results can contribute to generating the stability lobe, thereby verifying the stability distribution and spectral characteristics of both the simulated and measured signals. The new algorithm realizes static data communication and dynamic state updating between the dynamic and cutting force models at high frequencies, thereby balancing the simulation speed and prediction quality.

Research on design and milling performance of unequal gradient helix and variable pitch end mill

It is difficult to obtain excellent surface quality and dimensional accuracy of the low-rigidity frame and beam parts made by titanium alloy, due to the obvious vibration and large elastic deformation during side milling. The variable helix and pitch cutting tool is usually used to reduce vibration, which does not consider the unequable stiffness in the milling area. Therefore, the concept of Unequal Gradient Helix and Variable Pitch (UGHVP) is proposed in this research. The helix angles of the UGHVP vary with the stiffness of the milling area position, which will lead to milling forces and vibration decreasing as the stiffness weakens. As a result, the surface quality and dimensional accuracy will be increased, of which the advantages are analyzed. The mathematical models of the UGHVP circumferential cutting edges and groove sections are derived, which provide theoretical support for tool grinding. The models are visualized by numerical simulation. Finally, the comparison experiment with the conventional variable helix and pitch end mill was completed by side-milling the designed feature samples. The results showed that the milling forces perpendicular to the milling surface by the UGHVP were smaller and less fluctuating, which could obtain less elastic deformation theoretically. The milling vibration was smoother, especially when cutting in and out. Besides, the larger the axial depth of cut, the more obvious the superior performance of the UGHVP tool. Better surface quality and dimensional accuracy were obtained, which proved the excellent performance of the UGHVP.

Simulation of Particle Breakage in Vibration Mill Based on Tavares Model

In this paper, discrete element simulation software EDEM and Tavares crushing model were used to carry out numerical simulation research on the motion characteristics and crushing characteristics of materials in the MZ100 vibration mill during the grinding process. The influence of material characteristics, shape characteristics and filling rate of grinding media, vibration frequency, and amplitude of vibration mill on the efficiency and effect of vibration mill was analyzed. The factors affecting the distribution characteristics of the rotary center of mass and the low-energy region of the grinding medium in the grinding cavity are discussed. The extreme inflection point of the crushing efficiency of the grinding material in the grinding cavity with respect to the increase of the excitation frequency is obtained. In order to improve the grinding efficiency and reduce the low energy zone, the optimum process parameters of eccentric vibration grinding were discussed, which provided theoretical guidance for the efficient crushing of grinding materials.

Vibration Feedback Control for Robotic Bone Milling

Bone milling is commonly performed in many surgical interventions, but it often suffers from unpredictable deflection of the bone and potential damage to critical anatomical structures. In this study, a method is proposed to control the depth of cut based on the milling vibration monitored in real time. An accelerometer is mounted on the surgical power tool to record its vibration. In order to extract characteristic information from the acceleration signal, a quality factor is defined to select the optimal harmonic in the signal. A mapping is then established between the amplitude of the optimal harmonic and the depth of cut measured by a displacement sensor. During automatic milling in a single type of material, the depth of cut is estimated by inputting the current harmonic amplitude into the mapping, and the robot's position is adjusted based on the deviation between the desired and the estimated depth of cut. When the cutting area is located between the cancellous bone and the cortical bone, the depth of cut is calculated based on the mapping for the cancellous bone, the mapping for the cortical bone, and the percentage of these two tissues. Thus, automatic milling is also available in this area. Validation of the proposed method via automatic milling experiments shows effectiveness and stableness of the control algorithm, and the safety and efficiency are ensured.

Vibratory Crushing and Grinding Machinery Design-Analysis-Test-Simulation-Examples Book Review

Vibratory Crushing and Grinding Machinery: Design-Analysis-Test-Simulation-Examples is an applied technical monograph in the field of vibratory utilization engineering written by Prof. Hou Shujun and others and published by Chemical Industry Press. The work is divided into 10 chapters, Chapter 1 describes the model analysis and test of vibratory crushing and grinding process, Chapters 2-4 introduce the working principle, dynamics simulation analysis, typical cases and performance test of double-cavity jaw, double-cavity roll and cone vibrating crusher, Chapters 5-7 introduce the working principle, dynamics simulation analysis, performance and experimental study of single-cylinder double-excited, double-cylinder single- excited and single-cylinder single-excited double-rigid vibrating mill, etc. Chapter 8 introduces the working principle, dynamics simulation analysis, performance and experimental study of single-cylinder single- excited double-rigid vibrating mill, respectively. Chapter 8 introduces the working principle, kinematics and dynamics modeling and simulation analysis, rigid-scattered coupling modeling and simulation analysis of eccentric shaft type high-speed oscillating vibration mill, Chapter 9 introduces the working principle, gassolid coupling modeling, process parameters and structural parameters of heterocoastal horizontal ultrafine classification mill simulation test, and Chapter 10 describes the design of vibratory crushing and milling system. The work systematically summarizes the team's years of innovative research results, systematic and rich in content, theory and application, to a certain extent, to promote the development of the discipline of vibration utilization engineering, which gives a large number of engineering design cases for the personnel engaged in related scientific research and work are of high reference value.

(HfTiZrMnCr)B2 high entropy diboride ceramics: Synthesis mechanism, microstructural, mechanical and thermal characterization

This study explains the synthesis mechanism of (HfTiZrMnCr)B2 high entropy diboride ceramics prepared via a combined route consisting of ball milling and spark plasma sintering. Firstly, metal borides were in-house synthesized using mechanochemical synthesis and leaching processes under optimum conditions from metal oxides, B2O3 and Mg precursors. The (HfTiZr)B2 composition, chosen as the main composition, was hybridized with two different methods: planetary and vibratory ball milling. As a result of milling experiments, 6 h vibratory milling was determined as the optimum duration, and all compositions were produced by spark plasma sintering method (2000 °C, 30 MPa) following this optimum condition. Different compositions were used to see which one of the HfB2, TiB2, ZrB2 compounds acted as a host material. Based on the phase analyses, single-phase HEB structures, Ti-rich phases and Hf, Ti, Zr-oxides were observed in the microstructure. Detailed physical, microstructural, mechanical and termal characterizations were performed: the highest hardness values were observed in the (HfTiMnCr)B2 and (HfTiZrMnCr)B2 samples as ∼ 27 GPa, the lowest wear rate was recorded for the (HfTiZrMnCr)B2 sample as ∼2 × 10−6 Nm/mm3, and the highest oxidation resistance was achieved at the (HfZrMnCr)B2 and (HfTiMnCr)B2 samples as weight gains ∼ 1.90%.

Zirconia CAD/CAM machining vibrations related to zirconia blank shape and initial digital nesting.

To evaluate CAD/CAM milling vibrations related to zirconia disk design, framework, and location of digital crown nesting during zirconia soft milling. In the present in vitro study, 25 round zirconia disks of 98 mm (R group) and 15 D-shaped zirconia disks of 71 mm (D group) were placed in a 5-axis CAD/CAM milling unit. The R group had 3 crown milling sites (n = 75) and the D group had 2 crown milling sites (n = 30). In the R group, site A was located 57 mm, site B was 92 mm, and site C was 123 mm from the machine holder attachment. In the D group, site A was 57 mm and site C was 123 mm from the machine holder attachment. A vibration meter (VB-8200; Lutron) was connected to the disk holder, and data (mm/second) were collected during the milling process at the different nesting locations. One-way ANOVA with post-hoc tests and Bonferroni correction for multiple tests were used to compare the groups (α = 0.05). In the R group, site C exhibited the highest mean vibration values compared with site A (P = 0.001). The first and second cutting tools (2.5 and 1 mm) exhibited statistically significant differences between the D and R groups at milling sites A and C (P < 0.001 and P = 0.003, respectively). Milling vibration increased as the distance between the machine holder arm and a digitally nested site increased. Round zirconia disks induced higher vibration values compared with D-shaped disks.