Machines

6905 KiB

Open AccessArticle

Aeronautical Magnetic Torque Limiter for Passive Protection against Overloads

by Cristian Cristache, Efren Diez-Jimenez, Ignacio Valiente-Blanco, Juan Sanchez-Garcia-Casarrubios and Jose-Luis Perez-Diaz

Machines 2016, 4(3), 17; https://doi.org/10.3390/machines4030017 - 7 Sep 2016

Cited by 8 | Viewed by 5088

Abstract

Actual aerospace and defense technologies present multiple limitations that need to be overcome in order to evolve to less contaminating and more efficient aircraft solutions. Contactless technologies come with essential advantages such as the absence of wear and friction. This work describes the design, prototype, and performance test according to RTCA-DO-160 of an aeronautical magnetic torque limiter. The results show correct continuous transmission operation (2250 rpm and 24 Nm) from −50 °C to +90 °C. Moreover, overload protection has been demonstrated for more than 200 jamming events without damage or required maintenance to the device. Full article

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6848 KiB

Open AccessArticle

Self-Sensing Electromagnets for Robotic Tooling Systems: Combining Sensor and Actuator

by Tobias Kamf and Johan Abrahamsson

Machines 2016, 4(3), 16; https://doi.org/10.3390/machines4030016 - 10 Aug 2016

Cited by 9 | Viewed by 7212

Abstract

A low-cost method, which integrates distance sensing functionality into a switched electromagnet by using a hybrid switching mode and current ripple measurements, is proposed. The electromagnet is controlled by a micro-controller via a MOSFET H bridge, utilizing a comparator-based current control. Additionally, a method for calculating the inductance of the electromagnet and approximating the magnetic contact between the electromagnet and its target is also presented. The resulting tool is attached to an industrial robot, and the system performance using this setup is evaluated. Distance sensing in the range of 0 mm to 5.2 mm is demonstrated. It is also shown that the relation between magnetic contact, coil current and calculated inductance can be reduced to a predictive look-up table, enabling the quality of the magnetic contact to be estimated using minimal computational effort. Full article

(This article belongs to the Special Issue Robotic Machine Tools)

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5279 KiB

Open AccessArticle

Optimization Design and Performance Analysis of a PM Brushless Rotor Claw Pole Motor with FEM

by Zhenyang Zhang, Huijuan Liu and Tengfei Song

Machines 2016, 4(3), 15; https://doi.org/10.3390/machines4030015 - 7 Jul 2016

Cited by 6 | Viewed by 9386

Abstract

A new type of permanent magnet (PM) brushless claw pole motor (CPM) with soft magnetic composite (SMC) core is designed and analyzed in this paper. The PMs are mounted on the claw pole surface, and the three-phase stator windings are fed by variable-frequency three-phase AC currents. The advantages of the proposed CPM are that the slip rings on the rotor are cast off and it can achieve the efficiency improvement and higher power density. The effects of the claw-pole structure parameters, the air-gap length, and the PM thinner parameter of the proposed CPM on the output torque are investigated by using three-dimensional time-stepping finite element method (3D TS-FEM). The optimal rotor structure of the proposed CPM is obtained by using the response surface methodology (RSM) and the particle swarm optimization (PSO) method and the comparison of full-load performances of the proposed CPM with different material cores (SMC and silicon steel) is analyzed. Full article

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8682 KiB

Open AccessArticle

Open Source Laser Polymer Welding System: Design and Characterization of Linear Low-Density Polyethylene Multilayer Welds

by John J. Laureto, Serguei V. Dessiatoun, Michael M. Ohadi and Joshua M. Pearce

Machines 2016, 4(3), 14; https://doi.org/10.3390/machines4030014 - 1 Jul 2016

Cited by 9 | Viewed by 9460

Abstract

The use of lasers to weld polymer sheets provides a means of highly-adaptive and custom additive manufacturing for a wide array of industrial, medical, and end user/consumer applications. This paper provides an open source design for a laser polymer welding system, which can be fabricated with low-cost fused filament fabrication and off-the-shelf mechanical and electrical parts. The system is controlled with free and open source software and firmware. The operation of the machine is validated and the performance of the system is quantified for the mechanical properties (peak load) and weld width of linear low density polyethylene (LLDPE) lap welds manufactured with the system as a function of linear energy density. The results provide incident laser power and machine parameters that enable both dual (two layers) and multilayer (three layers while welding only two sheets) polymer welded systems. The application of these parameter sets provides users of the open source laser polymer welder with the fundamental requirements to produce mechanically stable LLDPE multi-layer welded products, such as heat exchangers. Full article

(This article belongs to the Special Issue Precision Manufacturing Processes)

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Machines, Volume 4, Issue 3 (September 2016) – 4 articles

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