Analysis of chattering phenomenon in industrial S6-high rolling mill

Chatter in rolling mills is the undesirable vibration observed in most of the rolling mills operating at high speed and rolling thin strip. In this work the authors discuss some problems relative to the vibrations occurring in a S6-high cold rolling mill. It can result in not good surface finish for some applications and, rare cases, in gauge variations in the rolled strip and it is considered to be the result of interaction between rolling mill structure and rolling-process. Three basic types of chatter can be classified in rolling mills: torsional, third-octave mode, and fifth-octave-mode chatter. S6-high rolling mill is an innovative mode to work the steel: it allows the use of very small work rolls laterally guided by individually adjustable side support rolls, which are supported by two rows of roller bearings mounted in cassettes. It has six rolls able to roll steel strip coming directly from hot rolling mill train. A proposed solution based on empirical observations, vibration analysis and considerations of a model is described with the aim to improve the quality of the product and increasing production

Contact mechanics analysis of a soft robotic fingerpad

The precision grasping capabilities of robotic hands is a key feature which is more and more required in the manipulation of objects in several unstructured fields, as for instance industrial, medical, agriculture and food industry. For this purpose, the realization of soft robotic fingers is crucial to reproduce the human finger skills. From this point of view the fingerpad is the part which is mostly involved in the contact. Particular attention must be paid to the knowledge of the mechanical contact behavior of soft artificial fingerpads. In this paper, artificial silicone fingerpads are applied to the last phalanx of robotic fingers actuated by tendons. The mechanical interaction between the fingerpad and a flat surface is analyzed in terms of deformations, contact areas and indentations. A reliable model of fingertip deformation properties provides important information for understanding robotic hand performance, that can be useful both in the design phase and for defining control strategies. The approach is based on theoretical, experimental, and numerical methods. The results will be exploited for the design of more effective robotic fingers for precision grasping of soft or fragile objects avoiding damages

Analysis of chattering phenomenon in industrial S6-high rolling mill. Part 2: Experimental study

The paper represents an extension of a previous work where the problem of chatter in a rolling mill producing advanced high-strength steels (AHSS) was investigated by a combination of a linear lumped parameter model and the slab analysis. In this paper the authors show the detailed experimental study of the problem with a complete description of all the phases related to the vibrational investigation that lead to the solution of the problem. Furthermore, a different model based on the Orowan’s method together with a nonlinear model of the rolling mill is presented and simulations are performed

Il ritorno della Geopolitica. Regioni e instabilità dal Mar Nero al Mar Caspio

Qual è il peso della geografia sulle dinamiche politiche globali? Lo spazio fisico e i vincoli che esso pone sono ancora così rilevanti in un’epoca in cui si parla sempre più di cybersecurity e big data? Con la fine della Guerra fredda alcuni avevano prefigurato la progressiva dematerializzazione delle relazioni internazionali, l’allentamento della competizione tra Stati e la loro inevitabile integrazione attraverso le Organizzazioni internazionali. Sin dal principio del XXI secolo, al contrario, la prossimità territoriale, un nuovo tipo di sfide all’ordine unipolare e la crisi di numerosi strumenti di governo multilaterali hanno riportato al centro dell’agenda politica la dimensione locale delle dinamiche di sicurezza – un processo che nello Spazio post-sovietico appare oltremodo evidente. Il ritorno della geopolitica. Regioni e instabilità dal Mar Nero al Mar Caspio si inserisce nel solco del rinato interesse verso quest’area e si serve del Caucaso meridionale come di un “laboratorio” attraverso il quale verificare empiricamente l’assunto generale da cui parte il volume: il dato territoriale continua a restare centrale nella comprensione sia delle cause della lotta per il potere nell’arena internazionale, sia delle sue modalità

Theoretical and Experimental Characterization of a New Robotic gripper’s Joint

Underactuation and compliant structures have been exploited in the design of robotic grippers and hands since these features allow to simplify the hardware and control structure of the gripper while maintaining a suitable level of robustness and adaptability with respect to task and environmental uncertainties. On the other hand, robotic fingers composed of deformable structures introduce new challenges in the kinematic and dynamic modelling, necessary both in the design and control phases. This paper presents the characterization of a new wave-shaped compliant joint that can be used to compose monolithic underactuated compliant fingers. The characterization has been performed both with numerical analyses and with experimental measures. Therefore, such identification will be used in the synthesis of underactuated grippers and other robotic devices

WOx/ZrO2 catalysts Part 4. Redox properties as investigated by redox cycles, XPS and EPR

The redox properties of wox/zro2 catalysts with W-content from 1.0 to 14.3 atoms nm-2, prepared by equilibrium adsorption from hydrous zirconium oxide and ammonium metatungstate solutions, were investigated by redox cycles with H2 and O2, volumetric oxygen adsorption at room temperature (RT), XPS and EPR. After catalysts were heated at 1073K in air, the various tungsten species (small WxOy clusters anchored to zirconia surface, polyoxotungstates species and crystalline WO3) reacted differently with H2 in the range 473-773K. The reduction degree of small W xOy clusters up to 723K slightly increased and then sharply increased, yielding at 773K an average oxidation state (nav) equal to 5.2. Conversely, the reduction degree of polyoxotungstates and WO 3 steeply increased from 523 to 773K, reaching nav equal to 4.8. XPS analysis disclosed that, after treatment in H2 at 773K, whereas W5+ formed on all the samples, W4+ species formed only in samples containing WO3 and polyoxotungstates. Depending on W-content, EPR detected various W5+ species in reduced ZW samples: isolated ions incorporated into the monoclinic zirconia; two kind of surface species, one in small clusters and the other in polyoxotungstates, resembling a bronze-like structure. The formation of O2 - by oxygen adsorption at RT gave an indirect evidence of isolated W5+ surface species, irrespective of W-content. Volumetric O2 adsorption indicated that W5+ surface species were largely re-oxidized at RT, whereas W4+ species, formed in polyoxotungstates and WO3, were less reactive, possibly because these species were less accessible to the gas phase. © 2004 Elsevier B.V. All rights reserved

Design of Multiple Wearable Robotic Extra Fingers for Human Hand Augmentation

Augmenting the human hand with robotic extra fingers is a cutting-edge research topic and has many potential applications, in particular as a compensatory and rehabilitation tool for patients with upper limb impairments. Devices composed of two extra fingers are preferred with respect to single finger devices when reliable grasps, resistance to external disturbances, and higher payloads are required. Underactuation and compliance are design choices that can reduce the device complexity and weight, maintaining the adaptability to different grasped objects. When only one motor is adopted to actuate multiple fingers, a differential mechanism is necessary to decouple finger movements and distribute forces. In this paper, the main features of a wearable device composed of two robotic extra fingers are described and analyzed in terms of kinematics, statics, and mechanical resistance. Each finger is composed of modular phalanges and is actuated with a single tendon. Interphalangeal joints include a passive elastic element that allows restoring the initial reference configuration when the tendon is released. The stiffness of each passive element can be customized in the manufacturing process and can be chosen according to a desired closure movement of the fingers. Another key aspect of the device is the differential system connecting the actuator to the fingers

Underactuated Soft Gripper for Helping Humans in Harmful Works

Robotics and automation are essential to improve life quality by assisting and substituting humans in dangerous tasks. Starting from this idea, this paper introduces an innovative gripper that can be employed in the new industrial policy, such as Industry 4.0, in which machines and humans work together. In particular, the paper describes the study of a new soft gripper as a modification of a underactuated gripper previously designed. The new proposed gripper presents an improved design, and it employs more sustainable materials resulting more compliant and adaptable. Therefore, it can be introduced within different industrial and service contexts with the aim of improving the process efficiency and even sustainability, according to SDG9. In particular, the proposed gripper can be used in the recycling and waste disposal chain with a consequent improvement of workers’ health, helping the achievement of SDG3, SDG8 and SDG12. The main feature of the gripper is the modularity, which makes it highly versatile and reconfigurable. reducing waste and obsolescence. In addition, the paper investigates the application of a new environment-friendly material for realising the phalanges comparing it with different materials in terms of structural mechanics by means of FEM analysis. Results demonstrate that both the new design and the employment of the new “green” material make the gripper more efficient and helpful in achieving different Sustainable Development Goals. This is also the basis of a circular perspective for the protection of the environment and the optimization of costs and resources and human lives