Desenvolvimento de um programa computacional para a integraÃÃo de dados de projeto, fabricaÃÃo e mediÃÃo de peÃas torneadas com Ãnfase na sÃntese de tolerÃncias dimensionais determinÃsticas

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

The objective of this work was to develop a computer program called Manufacturing Management System â SGF developed with the Excel language. This software integrates three stages: design, manufacturing by machining and measurement. So, itâs divided in three different and independent modules: design, manufacturing and measurement. In the design module is presented a methodology for determination of dimensional tolerances and their upper and lower limits of pieces produced by machining processes. In this determination is considered the interchangeability of the pieces, the kind of adjustment, precision degree, the precision of the machine tool, the finish surface and mechanical resistance. This software has a tolerance data bank with some examples of interchangeable pieces in different applications. In the manufacturing module, the computer program calculates the optimum machining parameters (feed, spindle and/or cutting velocity and cutting depth) of the turning process for determination of the total manufacturing cost and the total manufacturing time by piece. This software still calculates the cutting time and the tool life time. Initially, the objective of the measurement module is to make the selection of the dimensional measurement system more suited, amongst the more used in industry (scale, tape, caliper, micrometer, height gage, dial indicator, measuring microscope, coordinate measuring machine). This selection is made taking as base the uncertainty of measurement, the resolution of the measuring instrument, accuracy and functional tolerances calculated in the design module. After this, the computer program presents the result of measurement with the uncertainty of measurement and calculates the conformity zone and the upper and lower control limits. This module still presents the main concepts related to metrology, being able to be accessible in a fast way using key words. Finally, is presented in this work a new mathematical model to the deterministic tolerance synthesis. This model uses Linear Programming to determine such tolerances and the objective function is the minimum fabrication cost or minimum fabrication time necessaries for generation of the desired dimensions. The constraints of this model are based on the uncertainty in measurement or machine tool uncertainty. The models previously adopted consider only the variability of the process and its coefficients of capability. This practical many times will demand the manufacture of a great amount of pieces. This work still presents the influence of the machining parameters in the dimensional tolerances, as well as the differences obtained in the final dimensional tolerances; therefore, the equations of manufacturing cost or manufacturing time by piece presented in the objective function had been conceived in accordance with these parameters. The mathematical model developed in this work reflects the three phases of the product: design, manufacturing and measurement. The great advantage of the considered model is the reduced number of manufactured pieces in contrast of the model that works the variability 3 of the process.

ASSUNTO(S)

mediÃÃo dimensional programa computacional machining computer program engenharia mecanica usinagem dimensional measurement tolerance synthesis sÃntese de tolerÃncia

ACESSO AO ARTIGO

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