Data processing: generic control systems or specific application – Specific application – apparatus or process – Product assembly or manufacturing
Reexamination Certificate
1997-03-24
2001-04-24
Grant, William (Department: 2121)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Product assembly or manufacturing
C700S097000, C700S099000, C700S100000, C700S101000, C705S002000, C706S919000
Reexamination Certificate
active
06223092
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is directed to improvement of manufacturability of an article or product and/or reduction of manufacturing cost thereof. More specifically, the present invention is concerned with a method of quantitatively evaluating whether or not a designed structure of an article or product is easy to manufacture on the basis of relevant design information prepared or generated by using a computer-aided design system (hereinafter also referred to as the CAD processor in abbreviation), to thereby determine at an earlier stage of a design process a best or optimal design plan or plan and hence a best or optimal manufacturing or fabricating method from a plurality of design plans or plans inclusive of alternative proposals. The present invention is also concerned with a system for carrying out the method mentioned above.
Heretofore, there have been proposed a variety of evaluation methods which allows a design engineer to evaluate in a stage of a design procedure whether or not a product being designed has a structure easy to manufacture. According to a first method referred to as the design review method and adopted widely, the manufacturability (i.e., ease of manufacture) of an article or product as designed is determined by those skilled in the design, production, inspection and other techniques on the basis of their empirical knowledges or experiences, wherein those portions to be improved, if any, are pointed out by them. According to a second evaluation method also adopted generally, a process plan is created on the basis of a design drawing, and the costs involved in processability parts and/or assembling an article as designed as well as the time required therefor is estimated, whereon the expert engineer skilled in the technique for manufacturing the article or product of concern favorableness or satisfactoriness of the designed structure on the basis of the estimated values and his or her empirical knowledges. As third and fourth evaluation methods known heretofore, there can be mentioned those disclosed in an article entitled “KUMITATEYASUI SEKKEI (Design Easy To Implement)” and contained in “NIKKEI MECHANICAL” published Mar. 21, 1988, pp. 37-48.
According to the third method mentioned above, a part attaching process is analytically divided into several process elements, which are then imparted with respective evaluation scores determined in dependence on the degrees of easiness or difficulty in carrying out the process elements, wherein the processes required for attaching part are represented by the aforementioned process elements, and then assemblability (degree of susceptibility to assembling) of the article or product of concern as a whole is evaluated on the basis of the calculated totality of the evaluation scores imparted to the individual process elements while extracting those process elements which make the part attachments difficult.
In this conjunction, it should however be mentioned that there is contained in the article mentioned above neither teachings nor suggestions as to the method for assigning the evaluation scores, the method for totalization of the evaluation scores and others. Apparently, the design engineer determines an overall or synthetic optimality for a plural kinds or sorts of workabilities such as processability (degree of susceptibility to processing), assemblability (degree of susceptibility to assembling) and the like by relying on some means. However, in the case of the evaluation method mentioned above, the favorableness or satisfactoriness is decided rather intuitively without presenting definitely the ground for the decision.
According to the fourth method mentioned above, items to be checked are classified to alignability, positionability, chuckability, attachability and other features of parts are allocated with scores determined intuitively or empirically which represent degrees of easiness or difficulty of aligning, positioning, chucking, attaching and so forth of the parts. Upon evaluation of the assemblability of a given article as designed, the design engineer determines the presence or absence of the items for checking applicable to the article of concern and inputs them to the system, whereon the assemblability of the article as a whole is evaluated on the basis of a sum of the above-mentioned scores assigned to the selected items while those parts providing difficulty in assembling thereof are extracted. In conjunction with calculation for the totalization described above, it is reported in the article cited previously that for each of the individual parts, the scores mentioned above are subtracted or eliminated from the full mark of “100 points”, whereon the total score for all the relevant check items is determined, and improvement of the design is performed until the mean value of the total scores of the individual parts attains at least seventy points.
At this juncture, it is also noted that JP-A-61-59900 discloses a method for design improvement which is applied to assembling of a printed substrate package and according to which evaluation scores are determined and displayed by resorting to a procedure similar to the fourth method described above.
The first mentioned prior art evaluation method is of a qualitative nature rather than quantitative and is disadvantageous in that not a little difficulty is encountered in expressing objectively and quantitatively to what extent the structure of an article or product under evaluation is favorable or unfavorable (satisfactory or unsatisfactory) for manufacturing or how effective the improvement as attempted will be. Besides, this method suffers from a problem that it can be carried out only by those having sufficient skilfullness in the design and manufacture engineering. According to the second mentioned prior art evaluation method, the assembling cost can certainly be estimated for an article or product as a whole or for every individual part or for some of the parts constituting the article. However, it is difficult to decide merely on the basis of only the assembling costs whether the designed structure is well qualified or whether any further improvement is necessary. Moreover, this known method has a drawback that the evaluation requires not a few experiences and knowledges as well as lots of time for the calculations involved therein, which makes the evaluation very difficult. Besides, unless the design of the article of concern has been completed, evaluation itself is rendered difficult. Consequently, improvement or modification of the design as found necessary can not be done until the design has been completed, which in turn means that an intolerable lot of time and expenditure will be taken for any further improvement of the design once completed. Under the circumstances, many articles designed rather unsatisfactorily or unfavorably have to be transferred to a production line without undergoing the further improvement, thus giving rise to a problem that the attempt for enhancing the productivity and reducing the cost often encounters an obstacle.
In brief, the first and second methods described above suffer from the shortcomings mentioned below.
(1) Evaluation is not quantitative but qualitative by nature, making impossible the quantitative evaluation.
(2) Evaluation can be made only by those having an abundance of experience or some knowledge of evaluation procedure. Further, the synthetic satisfactoriness of a decision for a plurality of different types of works or processes can not be made while presenting explicitly the ground therefor.
(3) With the evaluation based only on such factors as the attachment/assembling cost and/or the processing cost, it is difficult to decide whether the design is satisfactory or not.
(4) Enormous labor or time is required for the evaluation.
(5) Evaluation can be made only after the design has been completed or at some time point close to the completion of the design, which makes it difficult to improve the design after the evaluation.
(6) It is difficult to improve the article or parts be
Arimoto Syoji
Hayakawa Mitsuharu
Ikeda Manabu
Iwata Minoru
Miyakawa Seii
Grant William
Hitachi , Ltd.
Mattingly Stanger & Malur, P.C.
Rodriguez Paul
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