Data processing: generic control systems or specific application – Specific application – apparatus or process – Product assembly or manufacturing
Reexamination Certificate
2000-03-16
2003-09-23
Picard, Leo (Department: 2125)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Product assembly or manufacturing
C702S185000
Reexamination Certificate
active
06625511
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method of estimating for evaluation a failure occurrence likelihood (real ability) of a manufacturing workshop upon manufacturing electric/electronic apparatuses for home use, products (or articles) for office-automation (OA) and the like by assembling or processing component parts therefor and an apparatus for carrying out the method, and additionally the invention concerns a product quality evaluation method for evaluating quality such as work-related fraction defective or work-related defective ratio and the like of products or articles such as those for home use, office automation (OA) and the like which are manufactured by assembling or processing component parts therefor and an apparatus for carrying out the method, and furthermore the invention concerns a recording medium storing therein a program or programs for executing the estimation/evaluation methods.
Most of the techniques known heretofore in this field are directed to estimation of causes for occurrence of failures or detects on the basis of phenomena which have actually taken place. As the hitherto known techniques for estimating the causes for the failures on the basis of the contents of phenomena actually taken place at the manufacturing stage, there can be mentioned the technique disclosed in JP-A-1-167631 (hereinafter referred to as the prior art 1) and JP-A-6-196900 (hereinafter referred to as the prior art 2). In the prior art 1, there is disclosed a work readjusting method according to which causes for failures or defects are defined in correspondence to combinations of passable/impassable items after inspection or examination of works, whereon degrees of correlation between the combinations of the passable/impassable items and the causes for failures or defects are estimated by taking into account remedying measures as taken, to thereby determine the cause for failure or defect on the basis of the degree of correlation between the combinations of passable/impassable items and the causes for failure or defect as estimated, whereon the cause for failure or defect as determined is removed by taking proper measures pertinent to the cause for failure or defect as determined. On the other hand, in the prior art 2, a method of analyzing defect factors in an electronic part packaging process is described, according to which quality data inputted at printing! mounting/soldering steps, respectively, in the electronic part packaging process are compared on a printed-circuit-board basis, to determine arithmetically the degree of influence of each of the above-mentioned steps exerted to the defectiveness of the finished product by referencing quality defectiveness regulation rules indicating possibilities of occurrence of defects in the individual steps.
Further, as the failure diagnosis techniques in which similar techniques are adopted, there may be mentioned, for example, those disclosed in JP-A-7-13517 (hereinafter referred to as the prior art 3) and JP-A-7-271587 (hereinafter referred to as the prior art 4). In the prior art 3, a method of estimating causes for unfavorable events is described, according to which phenomena representing statuses of unfavorable events and causes bringing about such unfavorable phenomena are compared on a phenomenon-by-phenomenon-basis for creating an association table in which there are defined association values indicating degrees of associations between phenomena and the relevant causes therefor, respectively, wherein phenomena taking place in accompanying an unfavorable event are discriminated and then values derived by weighing the association values relevant to the phenomena in accordance with a predetermined method are accumulatively summed up, and the cause for which the sum value is maximum is decided as the cause for the unfavorable event by referencing the association table. On the other hand, in the prior art 4, a failure diagnosis apparatus is described which is so arranged that a hypothesis is framed by investigating unfavorable phenomenon by making use of knowledge database stating definitely causes for failures and unfavorable phenomena, whereon the hypothesis mentioned above is verified by resorting to a knowledge database implemented by analyzing theoretically the causality relations between the unfavorable phenomena and the causes therefore.
All of the prior arts 1, 2, 3 and 4 mentioned above are directed to the techniques for estimating the causes having direct influence to the failure or defect event on the basis of the phenomena taken place actually in the past for allowing the proper remedying or repairing measures to be taken speedily at the time point of occurrence of failure phenomenon on the basis of the event actually taken place.
On the other hand, as a method or procedure for performing in advance a quality evaluation of an article to be manufactured before failure has actually occurred, there is known an FMEA (Failure Mode and Effects Analysis) technique (described in NIRKAGIREN: Reliability Engineering Ser. 7 “PRACTICAL USE OF FMEA, FTA”) which is primarily adopted at the stage of designing a product or article to be manufactured. According to this procedure, an evaluator himself or herself predicts failure phenomena which may occur in association with individual component parts constituting a product and summarizes the “failure phenomena relating to the individual parts in the form of a table. Thus, by referencing the table, the evaluator himself or herself can predict “what sort of influence a product to be manufactured will suffer when a failure takes place”. In this way, high-quality design having substantially no unintentional omissions can be realized.
Further, in conjunction with the FMEA method, there is known a procedure for estimating the degree of seriousness of defects and failures relating to individual component parts by determining the probability of occurrence of failure phenomena (defective ratios) as estimated by the evaluator in conjunction with the individual parts, whereon the degree of seriousness of defect of the product to be manufactured which can be regarded as being ascribable to the defect(s) of the individual parts is estimated, as in the case of FMECA (Failure Mode, Effects and Criticality Analysis) technique.
Additionally, there are known so-called subcontractor factory inspection/check sheet schema adopted generally by various enterprises for checking the subcontractors' factories for evaluating the factories' facility levels capable of manufacturing products of quality to be satisfied. Further, as other techniques for evaluating the productivities of the factories, there are known “factory diagnosis apparatus” (JP-A-9-62309) (prior art 5), and “diagnosis system for factories for packaging works” (JP-A-10-79599) (prior art 6).
SUMMARY OF THE INVENTION
However, none of the conventional methods or techniques mentioned above, i.e., the techniques for estimating the causes exerting influences straightforwardly to the failures or defects on the basis of the events which took place in the past, the FMEA method and the FMECA method, is not in the position to estimate the potential of failure to occur in a given product with high accuracy, because of the necessity to grasp substantially whole of the failure phenomena which may actually occur.
Such being the circumstances, in the current state of the art, not a few failures actually take place in the manufacturing works due to omission of examination and study, presenting one of the causes for deterioration of the quality of the manufactured articles.
Further, the subcontractor factory inspection! check sheet schema mentioned previously is inherently designed for evaluating organization and system of the factory under evaluation as to the facilities for the development, manufacture, quality securement and the like. However, it is impossible to estimate quantitatively the failure occurrence likelihood of the factory under evaluation on the basis of the results of the evaluation. Furthermore, with
Asano Masaaki
Kubota Takashi
Miyakawa Seii
Ohashi Toshijiro
Suzuki Tatsuya
Antonelli Terry Stout & Kraus LLP
Picard Leo
Rodriguez Paul
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