Applied Mechanics and Materials Vol. 245

Abstract: In small and medium batch series manufacturing the small tool and workpiece changing time is one of the main objectives to follow in obtaining high productivity. These auxiliary times are defined as the times consumed with preparing and changing the next tool or workpiece to follow the machining process, times that usually overlap the machining process. For this purpose machining centres are equipped with an automatic tool changer system and an automatic pallet changer system. The palletizing systems imply eliminating the times consumed with the alignment, fixing and clamping of the workpieces, these systems consisting of several mechanisms: the pallet, the automatic pallet changing mechanism, the positioning mechanism and the pallet clamp/unclamp mechanism. In this paper we present an general overview of the automatic pallet changing mechanisms used both in flexible manufacturing systems and machining centres.

Abstract: Carbon nanofibers have been utilized increasingly for enhancing the mechanical properties of advanced polymer composites, which include high strength, stiffness, toughness, and through-thickness Properties. The incorporation of nano particles with a high aspect ratio and extremely large surface area into polymers improves their mechanical properties significantly. Although a number of efforts have been made to improve various properties by mixing nano particles directly into resin, however, it could lead to high viscosities which create problems during processing. In this particular study, an attempt has been made to enhance mechanical response of nano composites by using, state of the art, a different technique i.e spraying the Carbon Nano Fibers (CNF) on dry perform before infusion. The nano composite samples were prepared using a spraying methodology i.e dispersing the 1.0 weight percent CNF solution on carbon fabric, and evaporating the solvent such that only nano fibers remain on perform, followed by Vacuum assisted resin transfer molding (VARTM). Tensile, compression, flexural and short beam strength tests were performed to evaluate the effectiveness of CNF addition on the mechanical properties of carbon / epoxy composites. Results indicated, CNF addition offered simultaneous increase in all these mechanical properties in different percentages i.e 22–28 percent improvement in tensile strength, 7-11 percent in compressive strength, 14–19 percent in Flexural strength and 45-55 percent short beam strength with respect to the neat composite. The rise in their modulus has also been discussed in detail and part of this study. For in-depth analysis, Microscopic approaches were also carried out to investigate the fracture behavior and mechanism of material. Scanning electron microscopy of fractured surfaces revealed improved primary fiber–matrix adhesion and indications of CNF-induced matrix toughening.

Abstract: The main purpose of the paper is to develop a neural network application destined to the raw material stock management, as an performant alternative to the classical models of costs stock management. Stocks of goods that manufacturers would classify as raw materials stocks are, in a special sense, goods in early stages of the production process. The testing was made for three companies from the automotive industry, but it could be applied to any kind of Romanian organization.

Abstract: Present article is focusing to the control of the coiler devices of an extrusion press of 2500 tons-force used in order to obtain coiled wires of brass and copper. The driving of coiler devices is done by another hydraulic system than the main hydraulic system of extrusion machine, with 2 rotary hydraulic motors for each coiling unit. Maintaining the synchronization between the speed of press’s ram during the pressing and the rotation of coilers during the coiling, in case of hydraulic driving, is a difficult task and the main goal of present paper.

Abstract: Finding productive performance of a producer is a topical issue on the basis of which has been and are done a large number of research. Currently there are several productive performance measurement techniques detailed in various forms, among which the most used are the efficiency and the productivity. The work presents the comparative measurement of the efficiency and productivity for a processing activity of specific products from machines constructions, organized in several enterprises in the area of N-V of Romania, between the intervals 2005-2010. This study uses data envelopment analysis (DEA) to measure the utilization capacity in six enterprises. Malmquist index method used in this research indicates that there is the tendency to increase or decrease the productivity and efficiency of the studied enterprises. Identification of positive or negative trend productive performance can be used to prepare a strategy of reducing inefficiencies and improving effectiveness of production process. Specifically, this study quantifies the level of technical efficiency and technical change in this particular manufacturing sector.

Abstract: The spindle assembly is the most essential parts of the machine tool. The dynamic characteristics of the spindle assembly affect the performance of NC machine tool and for this reason should be studied. This paper presents a comparative analysis of theoretical and experimental dynamic behavior of no-load operation of a spindle for a vertical milling machine. Research has been conducted to highlight the natural vibrations mode and the directions that the system is more rigid. Study presents a support for the spindle analysis, so that the adoption of a constructive solution to be optimal.

Abstract: The article deals with a solution of selected problems associated with evaluation of armoured vehicles flotation ability. Main attention is devoted to analysis of possible methods of vehicle ability evaluation to pass over a water obstacle with respect to its current speed.

Abstract: This paper aims to present a first part of research carried out on pneumatic muscles. The first applications of these actuators were in the innovative research areas as: rehabilitation medical equipments, prosthesis, robotics and exoskeletons. Despite of a large number of applications, theoretical and experimental research in this area are not many, due to there complex structure in which are used new materials, a combination synthetic rubber membrane and polymers fibers. In this article will be presented the experimental results of a specific pneumatic muscle based on which it will be realized a mathematical model to describe its behavior and to determine the parameters that influence largely static and dynamic feature.

Abstract: The present paper is focused on integration TCP-IP devices into smart house projects. The designed devices will send data to web application. The proposed implementation starts from server sent events for real time measurements and from X10 protocol- based devices for energy metering. In the paper we analyze hardware and software designing principles and architectures around a microcontroller application. Some real time and offline results are shown and analyzed. All the applications are successful tested in different projects, then integrated in present application.

Abstract: Wheels and legs are two widely accepted methodology used to move the moving platform to the ground. Wheels are human inventions, the rolls in a straight country excel in energy efficiency and speed of movement. Hybrid platform for integrating the benefits of legs and wheels with high mobility of both seems to be the "future" of mobile platforms for indoor and outdoor environment. This paper describes the design leg-wheel chassis for service robot.