Volume 17, Issue 2, 2022/Journal Proceedings in Manufacturing Systems

Abstract: In this work, some of the theoretical and practical researches and achievements of the authors regarding the lubrication of the guides of heavy machine tools are presented. Calculation methods, simulations and the practical achievements used and obtained on the modernization or remanufacturing of heavy machine-tools, such as: carousel lathes, boring and milling machines (AF) and gantry type milling machines, are presented. The work deals with the intermittent lubrication of the guides of these machines with the help of typical elements and systems, offered by different manufacturers of such equipment.

Key words: machine tools, guideways, lubrication systems, lubrication calculation, simulation.

pp. 47-53 View full text

Design of mechatronic modules that can form multiple configurations of mobile robots

Adrian MAROȘAN^1,*, George CONSTANTIN², Anca Lucia CHICEA³, Mihai CRENGANIȘ⁴, Fineas MORARIU⁵

^1,Assist. Prof., PhD Student, Robots and Manufacturing Systems Department, University "Politehnica" of Bucharest, Romania

²⁾ Prof., PhD, Robots and Manufacturing Systems Department, University "Politehnica" of Bucharest, Romania

³⁾ Conf., PhD, Machines and Industrial Equipment, University "Lucian Blaga" of Sibiu, Faculty of Engineering, Romania

⁴⁾ Lecturer, PhD, Machines and Industrial Equipment, University "Lucian Blaga" of Sibiu, Faculty of Engineering, Romania

⁵⁾ Assist. Prof., PhD Student, Department of Machines and Industrial Equipment, "Lucian Blaga" University of Sibiu, Sibiu, Romania

Abstract: The ever-changing industrial environment has become very competitive these days, and industries such as the automotive industry are trying to find increasingly complex automation solutions that can lead to an increase in targeted productivity in several stages, from the supply of semi-finished products to the delivery of the final product. Solutions for automating the logistics system exist but can be greatly improved to increase productivity and reduce production costs. This paper presents the design of mechatronic modules that can form multiple configurations of modular mobile robots with multiple wheel types. In addition, the paper discusses the configuration of a mobile robot with four omnidirectional wheels having rollers arranged at 90 degrees. For this configuration, the constructive variants, the functionality of the subassemblies and the mathematical modelling of the kinematic and dynamic model are presented.

Key words: Mobile robots, Modular robots, Reconfigurable, Omnidirectional, Kinematics, Robot dynamics, mechatronic system.

pp. 55-61 View fullext

The effect of the process parameters and light curing process on the dimensional accuracy of the 3D-printed holes

Mariana-Cristiana IACOB¹, Diana POPESCU^2,*

¹⁾ Eng., Ph.D. Student, Robotics and Production Systems Department, University Politehnica of Bucharest, Bucharest, 06042, Romania

²⁾ Prof., Ph.D., Robotics and Manufacturing Systems Department, University "Politehnica" of Bucharest, Romania

Abstract: The paper presents an investigation on the influence of the parameter settings and 405 nm wavelength light curing on the dimensional accuracy of 3D-printed holes included in prints manufactured by the material extrusion process (MEX). The hole feature is typically used to enable the assembly of 3D-printed parts by means of fasteners. As the bolt-hole clearance affects the quality and stiffness of the assembly, it becomes relevant to understand how to tune different 3D printing process parameters for achieving an actual clearance as close as possible to the nominal one. It is also relevant to understand how this is affected by different work conditions, such as violet-blue light exposure which is used for its antimicrobial properties. Different values of three parameters (printing speed, layer thickness, number of perimeters) were set for manufacturing test parts that were then subjected to 48 hours light curing. All prints were made of polylactic acid and 3D printed on a Prusa Replica 3D printer. The combined effect of the parameter settings and light treatment was also analyzed. The results showed a decrease in the holes’ diameters regardless of the printing settings, the shrinkage being more significant for the holes with the smallest diameter (6 mm). Regarding the dimensional accuracy, layer thickness was the most influential printing parameter. However, a trade-off between printing time and cost, and dimensional accuracy should be considered by the designers.

Keywords: 3D printing, holes, process parameters, dimensional accuracy, 405 nm light curing.

pp. 63-67 View full text

Autonomous lawn mowers ‒ A comparative approach

Fineas MORARIU^1*, Sever-Gabriel RACZ²

¹⁾ Assist. Prof., PhD Student, Department of Machines and Industrial Equipment, "Lucian Blaga" University of Sibiu, Sibiu, Romania

²⁾ Prof., PhD, Department of Machines and Industrial Equipment, "Lucian Blaga" University of Sibiu , Sibiu, Romania

Abstract: The service mobile robot market is increasingly growing. Autonomous electric lawn mowers, as part of this category of robots, pose numerous advantages for the user in what concerns the time spent conventionally mowing the lawn, the consumption of energy, and safety. Moreover, the original cost of investment and of the spare parts must be taken into account. Autonomous electric lawn mowers save the operators from repetitively doing the same job. Once the area is defined with the help of a boundary wire, the robot moves randomly, based on the navigation strategy, with trajectories that have not been previously defined, autonomously avoiding obstacles within the area, with the help of sensors. Well-known and experienced garden equipment manufacturers offer a wide variety of autonomous robots. This paper provides an insight into the field and the research trends concerning operational safety, energy efficiency, and navigation of autonomous electric lawn mowers. In this research paper, some of the most representative types of robots are compared, taking into account essential criteria for these types of robots, such as: the recommended mowed area, the robot autonomy under normal conditions of use, navigation modes and strategies, the cutting system, control, mobile applications and optional functions.

Key words: Mobile Robots, Lawn mowers, Autonomous navigation, Efficiency, Autonomy, Operational safety.

pp. 69-77 View full text

QO-Cardsat microsatellite calculation methodology of the position of the joints and required torque to open the panels

Dorel Florea ANANIA^1,*, Emilia BĂLAN², Miron ZAPCIU³, Marilena STOICA⁴, Andra Elena PENA⁵

^{1, 2)} Assoc. Prof., PhD Eng., Robots and Production Systems Department, University "Politehnica" of Bucharest, Romania

³⁾ Prof., PhD Eng., Robots and Production Systems Department, University "Politehnica" of Bucharest, Romania

⁴⁾ Lecturer, PhD Eng., Department of Machine Elements and Tribology, University "Politehnica" of Bucharest, Romania

⁵⁾ Lecturer, PhD Eng., Robots and Production Systems Department, University "Politehnica" of Bucharest, Romania

Abstract: Microsatellites are the subject of many research projects addressed today in universities. The most successful microsatellites known are the CubeSats. An objective of this paper is to establish an optimal configuration of the structure of a microsatellite composed of several panels named Cardsat. A Cardsat is a thin panel-shaped satellite with low volume and weight. It is designed to perform the same functions as the CubeSat, but with a much smaller volume (up to 11 times smaller). In order to launch, the panels are folded and assembled by means of joints. They form a package. This paper presents a method for load calculation of a flexible structure QO-Cardsat used in microsatellite architecture for deploying into predefined configuration. The results presented in this article are the preliminary calculations necessary for the design of the actuation elements of the Cardsat type panels in a combined construction so that it is possible to open in the final configuration starting from the folded form required for the launch. The steps required for the technical design of the proposed panel configurations are: kinematic calculation to identify the position of the panels and their centers of mass for given angles, calculation of the resistant moments required to be overcome by the actuating elements of the spring type, calculation of springs (torsion/lamination). The calculation of the joint positions is carried out with the help of rotation matrices.

Key words: microsatellite, configuration, QO-Cardsat, matrix joints calculation, opening torque.

Electronic mail: orgcom@icmas.eu