Automatic assembly design project 1968/69: report of the control and motivation committee

Methods of control for automatic assembly machines are surveyed. The control requirements of the versatile automatic assembly machine are analysed, and the most practical system is specified and designed in detail

Index to NASA Tech Briefs, 1975

This index contains abstracts and four indexes--subject, personal author, originating Center, and Tech Brief number--for 1975 Tech Briefs

Development and characteristics of the hardware for Skylab experiment S015

Details are given regarding the hardware for the Skylab S015 experiment, which was designed to detect the effects of zero gravity on cell growth rates. Experience gained in hardware-related considerations is presented for use of researchers concerned with future research of this type and further study of the S015 results. Brief descriptions are given of the experiment hardware, the hardware configuration for the critical design review, the major configuration changes, the final configuration, and the postflight review and analysis. An appendix describes pertinent documentation, film, and hardware that are available to qualified researchers; sources for additional or special information are given

Wire and arc additive manufacturing: equipment development and parts characterization

Wire and arc additive manufacturing (WAAM) is finding applications in different industrial sectors where it shows to be competitive compared to laser based additive manufacturing technologies. Two major advantages are associated to WAAM: it is a low capital investment technology with reduced running and maintenance costs and allows to manufacture parts with insipient or no porosities. This study aimed at testing and validating a three-axis positioning system designed and manufactured at Mechanical Technology Group of Mechanical and Industrial Engineering Department at Nova University. The major characteristics of the developed system are the following: 4.5 m3 working space, a maximum travel speed of 59 mm/s for the X and Y axes and of 2 mm/s for the Z axis. A maximum positional deviation of 0.02 mm, a minimal travel speed deviation of 0.24 mm/s and a displacement of 0.2 mm of the welding torch due to vibrations during a unidirectional movement. The equipment was validated by manufacturing thin walls by deposition of a high strength low alloy (HSLA) steel wire with Gas Metal Arc Welding (GMAW), monitoring the thermal cycles by infrared thermography to evaluate them in different layers. Geometrical, microstructural and mechanical characterization of parts was performed. Manufactured parts exhibited good surface finishing measured by the surface waviness that was around 300 μm and no internal defects were observed. Parts were isotropic as far as microstructural features and mechanical performance are concerned. The microstructure was mainly constituted by acicular ferrite and perlite with hardness below 320 HV. Energy dispersive spectrometry was performed, and no element loss was identified. Ultimate tensile strength varied between 700 and 809 MPa, depending on the process parameters. Resistance to impact was assessed by Charpy V impact tests with reduced size specimens and the absorbed energy registered was of 15 and 18 J, in longitudinal (Y) and normal (Z) directions, respectively. A ductile fracture surface was observed which is also a relevant indicator of mechanical performance of parts produced by WAAM in a HSLA steel

Design and Analysis of a Labview and Arduino-Based Automatic Solar Tracking System

A Thesis Presented to the Faculty of the College of Science and Technology Morehead State University in Partial Fulfillment of the requirements for the Degree Master of Science by Caiwen Ding April 24, 201

Design and manufacturing of a Selective Laser Sintering test bench to test sintering materials

The goal of this project is to design and build a prototype of recoating system for a laser cutting machine to turn it into a selective laser sintering printing machine. This prototype will be used to study new sintering materials and to design, if decided, a SLS 3D printing Machine (Selective Laser Sintering). This project has been developed in the installations and funded by Fundació CIM. The project develops the mechanical design and the electronic system design. Both parts are explained on this paper, so new users can use the machine and can understand the system. With this paper, it is expected that it can be improved in a future to test other parameters and configurations. The paper is divided in three basic blocks that are summed up here: The first block is an introduction to the 3D printing technologies. The most used of them are explained and selective laser sintering is explained in deep. With this block the reader can understand why it is important to develop the SLS technology and what has to be done to improve the machines and the technology. The second block is a discussion on the mechanical design of the machine. The general idea of the machine is explained so the user can understand why the machine is designed in this way. After that, each part is detailed to see how the different mechanical challenges where overtaken. At the end of the block, there is a small calculations section needed on the electronic part. The third block is an extensive explanation of the electronic system that controls and moves the machine. In that block, the different components are explained so the user can understand its basics working principles. It is also explained how the selection of the electronic components was done. Then everything is put together to see the whole electronic system. Along with this paper, there are annexes that provide some extra information for the reader. One of this annexes refers to the mechanical part and the other one has some datasheets and coding for the electronic section. The whole design has been done in SOLIDWORKS cad software and its electric extension ELECWORKS. The programming job was done with Arduino compiler

DC-Link Voltage Coordinated-Proportional Control for Cascaded Converter with Zero Steady-State Error and Reduced System Type

copyright 2015 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.Cascaded converter is formed by connecting two sub-converters together, sharing a common intermediate DC-link voltage. Regulation of this DC-link voltage is frequently realized with a Proportional-Integral (PI) controller, whose high gain at DC helps to force a zero steady-state tracking error. Such precise tracking is however at the expense of increasing the system type, caused by the extra pole at the origin introduced by the PI controller. The overall system may hence be tougher to control. To reduce the system type while preserving precise DC-link voltage tracking, this paper proposes a coordinated control scheme for the cascaded converter, which uses only a proportional DC-link voltage regulator. The resulting converter is thus dynamically faster, and when compared with the conventional PI-controlled converter, it is less affected by impedance interaction between its two sub-converters. The proposed scheme can be used with either unidirectional or bidirectional power flow, and has been verified by simulation and experimental results presented in the paper

Space programs summary no. 37-63, volume 1 for the period 1 March - 30 April 1970. Flight projects

Mariner Mars 1971, Mariner Venus-Mercury 1973 and Viking Orbiter 1975 status report

Design and validation of an innovative 3D printer containing a co-rotating twin screw extrusion unit

This paper presents the design and validation of an innovative 3D printer containing a co-rotating twin screw extrusion unit (Co-TSE). Single screw print heads were developed in the mid-2000s as an alternative to filament-based 3D printers, but they have limited process flexibility and mixing capacity. The new design accepts material in powder or micro-pellet form, and its dispersive and distributive mixing capacity can be fine tuned by setting output and screw rotation speed independently. The design combines a miniaturized modular Co-TSE operated under starve-fed conditions with a benchtop Cartesian platform. Numerical calculations were performed to ascertain whether the appropriate thermomechanical environment for polymer processing could be created by the proposed design. A prototype was built and extrusion tests were performed under different operating conditions, using polypropylene and a 90/10 wt% polypropylene/polystyrene blend. Two screw configurations were used, with and without kneading discs, to assess the response of the extrusion unit in terms of flow characteristics and mixing performance. The restriction to flow created by the mixing elements determines the starting melt position, and the average residence times, while their shearing and extensional action enhances homogenization effectiveness. The screw configuration and rotation speed do not affect the output, which depends only on the feed rate. Preliminary deposition tests were conducted to determine the feasible printing parameters. A standard tensile test specimen, a square scaffold and a multicolored rectangular box were successfully printed, validating the innovative design. The mechanical properties of printed test specimens were within the expected values.This work was supported by the National Council for Scientific and Technological Development (CNPq), grants 2016-4/442109 and 142348/2018-0, and by the Coordination for the Improvement of Higher Education Personnel (CAPES), finance code 001