A design of DSS for mass production machining systems

http://bulletin.pan.pl/(57-3)265.pdfInternational audienceIn this paper, we present a decision support tool (DSS) for preliminary design of transfer machines with rotary or mobile tables. In these transfer machines, the machining operations are executed on working positions equipped by standard multi-spindle heads. A part is sequentially machined on m working positions and is moved from one position to the next using a rotary or a mobile table. The operations are grouped into blocks, where the operations of the same block are simultaneously performed by one multi-spindle head. At the preliminary design stage, the goal is to select the number of working positions and to decide which spindle heads will be installed minimizing the machine cost while respecting a given production rate. The paper presents the overall approach and depicts mathematical and decision-support methods developed and implemented in a software for the optimization of preliminary design (or reconfiguration) of such machining systems

An Unified Approach to Find an Optimal Parameterized Path in a Digraph with Multiple Features

This paper is devoted to a class of problems which are modeled by a digraph, and such that each arc is characterized by several weights which depend on a parameter. This parameter takes its values in a set which characterizes the arc. The goal is to find a so-called parameterized path (i.e; a path and the values of the parameters corresponding to its arcs) that optimizes a criterion which is a combination of the weights of the arcs. The problem is introduced using transportation, communication and manufacturing problems. An unified formulation is provided, as well as an algorithm. A numerical example is proposed to illustrate this algorithm

Une Approche de plus court chemin pour l'optimisation des machines-outils

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Optimization of power transmission systems using a multi-level decomposition approach

We discuss the use of operations research methods for computer-aided design of mechanical transmission systems. We consider how to choose simultaneously transmission ratios and basic design parameters of transmission elements (diameters, widths, modules and tooth number for gears, diameters of shafts). The objectives, by the order of importance, are: to minimize the deviation of the obtained speeds from desired; to maximize the transmission life; to minimize the total mass. To solve this problem, we propose a multi-level decomposition scheme in combination with methods of quadratic and dynamic programming. Some industrial cases are solved. For these cases, the developed software tool improves the design decisions by decreasing total metal consumption of the transmission as much as 7–10% and considerable simplifies the work of the designer

Optimisation of the aggregation and execution rates for intersecting operation sets: an example of machining process design

International audienceA sequence of multiple parts is processed on a multi-position transfer line of conveyor type. This sequence consists of identical subsequences (batches). The sets of operations executed for each part at each position are given and these sets for different parts can intersect. Some operations executed at one position can be aggregated into blocks of operations. Each block is executed at a uniform rate (in particular, feed per minute) by a common drive unit. The set of potentially feasible blocks is specified. We consider the situation when the sets of operations for different blocks do not intersect and each potential block can be executed either completely aggregated (i.e. as one block) or completely disaggregated (individually). Aggregation reduces the investment costs, but can increase the consumption of tools due to excluding the individual selection of rates for aggregated operations. The accepted option of the aggregation and the rates of operations remain invariable during the line functioning. The problem is to select the optimal option of aggregation and rates of all operations that minimize the total batch processing cost while ensuring the required line productivity. A mathematical model of the problem and a two-level decomposition method for its solution are proposed. The statement of the problem and the results of its solution are illustrated on a real industrial example. The developed model and method can be applied to solve similar problems arising in other domains

Graph approach for design of unit-head machines with a rotary table

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Methods of Optimization for Aggregation and Execution Modes of Steps for Multi-positional Batch Processing

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Optimization of Multi-Tool Cutting Modes in Multi-Item Batch Manufacturing System

International audienceThe problem of optimization of cutting modes for multiple position machines and transfer lines equipped with multi-spindle heads is considered. Parts of several types are grouped into batches. Each tool can be used for machining different parts of a batch. The cutting modes to be defined should provide a required throughput, meet the constraints on the cutting process characteristics and minimize the batch production cost. Decomposition techniques are proposed. These techniques are based on the method of Lagrange multipliers, the concept of fragmentary parameterization and techniques for separable programming problems

Reducing transfer balancing problem with known blocks and parallel activation mode to a set partitioning problem

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A Decomposition Method for Transfer Line Life Cycle Cost Optimisation

International audienceA new method to search best parameters of a transfer line so that the cost of each manufactured part will be minimised. The synchronised transfer lines with parallel machining are considered. Such lines are widely used in mass and large-scale mechanical production. The objective is to minimise the line life cycle cost per part under the given productivity and technological constraints. The design decisions to be optimised are: number of spindles and workstations. This will be accomplished by defining subsets of tasks which are performed by one spindle head and cutting conditions for each spindle. The paper focuses on a mathematical model of the problem and methods used to solve it. This model is formulated in terms of mixed (discrete and non-linear) programming and graph theory. A special decomposition scheme based on the parametric decomposition technique is proposed. For solving the sub-problems obtained after decomposition, a Branch-and-Bound algorithm as well as a shortest path technique are used