39,424 research outputs found
Design for manufacturability : re-design of pencil sharpener for the ease of assembly
A Design For Manufacturability (DFM) approach is used to analyze the existing design of a pencil sharpener, and to reduce and re-design the parts of pencil sharpener for the ease of assembly. The procedure for the selection of a suitable and economical assembly method is based on the Boothroyd and Dewhurst methods. Analysis of the initial design for manual assembly and re-design for automatic as well as manual assembly is presented. An algorithmic approach for simplified generation of all mechanical assembly sequences and selection of the assembly sequences is presented using De Fazio and Whitney approach
Design for assembly : re-design of an electrical switch for the ease of automatic assembly
A design for assembly (DFA) method is used to analyze the existing design of parts of an electrical switch, and to reduce and re-design them, for the ease of automatic assembly. The procedure for the selection of suitable and economical assembly method is presented based on the Boothroyd & Dewhurst methods. Analysis of the initial design for manual assembly and the re-design for automatic assembly are presented. An algorithmic approach for simplified generation of all mechanical assembly sequences and selecting the good assembly sequences is presented with graphical representations. A work station needed for the automatic assembly is developed, which incorporates vibratory bowl feeders, an indexing machine and other equipment
An assembly oriented design framework for product structure engineering and assembly sequence planning
The paper describes a novel framework for an assembly-oriented design (AOD) approach as a new functional product lifecycle management (PLM) strategy, by considering product design and assembly sequence planning phases concurrently. Integration issues of product life cycle into the product development process have received much attention over the last two decades, especially at the detailed design stage. The main objective of the research is to define assembly sequence into preliminary design stages by introducing and applying assembly process knowledge in order to provide an assembly context knowledge to support life-oriented product development process, particularly for product structuring. The proposed framework highlights a novel algorithm based on a mathematical model integrating boundary conditions related to DFA rules, engineering decisions for assembly sequence and the product structure definition. This framework has been implemented in a new system called PEGASUS considered as an AOD module for a PLM system. A case study of applying the framework to a catalytic-converter and diesel particulate filter sub-system, belonging to an exhaust system from an industrial automotive supplier, is introduced to illustrate the efficiency of the proposed AOD methodology
Precedence relationship representations of mechanical assembly sequences
Two types of precedence relationship representations for mechanical assembly sequences are presented: precedence relationships between the establishment of one connection between two parts and the establishment of another connection, and precedence relationships between the establishment of one connection and states of the assembly process. Precedence relationship representations have the advantage of being very compact. The problem with these representations was how to guarantee their correctness and completeness. Two theorems are presented each of which leads to the generation of one type of precedence relationship representation guaranteeing its correctness and completeness for a class of assemblies
A model for assembly sequence planning in a multirobot environment
2002 IFAC15th Triennial World Congress, Barcelona, SpainThis paper presents a model for the selection of optimal assembly sequences for a product in multirobot systems. The objective of the plan is the minimization of the total assembly time (makespan). To meet this objective, the model takes into account, in addition to the assembly times and resources for each task, the times needed to change tools in the robots, and the delays due to the transportation of intermediate subassemblies between different machines. An A* algorithm that solves the problem is also presented, which starts from the And/Or graph for the product (compressed representation of all feasible assembly plans)
A CSP model for simple non-reversible and parallel repair plans
Thiswork presents a constraint satisfaction problem
(CSP) model for the planning and scheduling of disassembly
and assembly tasks when repairing or substituting
faulty parts. The problem involves not only the ordering of
assembly and disassembly tasks, but also the selection of
them from a set of alternatives. The goal of the plan is the minimization
of the total repairing time, and the model considers,
apart from the durations and resources used for the assembly
and disassembly tasks, the necessary delays due to the change
of configuration in the machines, and to the transportation
of intermediate subassemblies between different machines.
The problem considers that sub-assemblies that do not contain
the faulty part are nor further disassembled, but allows
non-reversible and parallel repair plans. The set of all feasible
repair plans are represented by an extended And/Or graph.
This extended representation embodies all of the constraints
of the problem, such as temporal and resource constraints and
those related to the selection of tasks for obtaining a correct
plan.Ministerio de Educación y Ciencia DIP2006-15476-C02-0
Combining Heuristics in Assembly Sequence Planning
Assembly Sequence Planning is tackled by modelling and solving a
planning problem that considers the execution of the plan in a system with multiple
assembly machines. The objective of the plan is the minimization of the total
assembly time (makespan). To meet this objective, the model takes into account the
durations and resources for the assembly tasks, the change of configuration in the
machines, and the transportation of intermediate subassemblies between different
workstations. In order to solve the problem, different heuristics has been defined
from two relaxed model of it, one considering only the precedence constraints among
tasks, and the other one considering only the use of shared resources. From these
basic heuristics, other ones have been defined, combining both types of information
from the problem, so that the refinement produces substantial improvements over the
initial heuristics.Ministerio de Ciencia y TecnologíaDPI2003-07146-C02-0
Impact of low gravity on water electrolysis operation
Advanced space missions will require oxygen and hydrogen utilities for several important operations including the following: (1) propulsion; (2) electrical power generation and storage; (3) environmental control and life support; (4) extravehicular activity; (5) in-space manufacturing and (6) in-space science activities. An experiment suited to a Space Shuttle standard middeck payload has been designed for the Static Feed Water Electrolysis technology which has been viewed as being capable of efficient, reliable oxygen and hydrogen generation with few subsystem components. The program included: end use design requirements, phenomena to be studied, Space Shuttle Orbiter experiment constraints, experiment design and data requirements, and test hardware requirements. The objectives are to obtain scientific and engineering data for future research and development and to focus on demonstrating and monitoring for safety of a standard middeck payload
An integrated representation scheme for assembly sequence planning and assembly line balancing
In a typical assembly optimisation, Assembly Sequence Planning and Assembly Line Balancing are
performed independently. However, competition has compelled the manufacturer to innovate by
integrating the optimisation of both problems. To incorporate ASP and ALB optimisations into a single
integrated optimisation, a clear prerequisite is the availability of integrated ASP and ALB representation.
Although many assembly representation works has been proposed, none of them fully meet the
requirements of integrated optimisation because they were developed independently from various needs.
In this paper, an integrated representation scheme for ASP and ALB that incorporate essential
optimisation information is developed. The proposed representation scheme is built based on assembly
tasks and represented using precedence graph and data matrix. The outcome from presented example
showed that the information for ASP and ALB optimisation can be integrated and represented using task based
precedence graph and data matrix, without discarding important attributes
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