Data processing: generic control systems or specific application – Specific application – apparatus or process – Product assembly or manufacturing
Reexamination Certificate
1998-06-19
2001-05-01
Beausoleil, Robert (Department: 2181)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Product assembly or manufacturing
C700S101000, C700S108000, C700S115000
Reexamination Certificate
active
06226561
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a production planning system, or more in particular to a production planning system including the elimination of deficient parts, elimination of superfluous parts, adjustment of a production plan and adjustment of a parts acquisition plan.
Well-known techniques for a production planning system include
(1) the technique described in JP-A-5-108661
(2) the technique described in JP-A-5-342220
The conventional technique disclosed in JP-A-5-108661 is a production scheduling system in which a production schedule solution of minimum cost is predetermined as an optimum solution according to mathematical programming, and the rationality of the artificial operation is sought after by indicating the effect that the artificial correction of the schedule has on the minimum cost.
The conventional technique (2) disclosed in JP-A-5-342220, on the other hand, is a process planning evaluation system in which a process planning is quantitatively evaluated by converting the amount of a product in stock and the rate of a product out of stock into a cost and simulating the change of the particular cost.
The production scheduling system according to the conventional technique (1) described above seeks after the rationality of the artificial operation by executing the following steps. Specifically, a time schedule is determined for actually carrying out the production based on the line, quantity and the delivery time of a product to be manufactured under such restraints as the product quantity, delivery time, the lead time for acquisition of raw materials and the maximum available workforce. In determining this time schedule, the actual restraints are approximated or simplified to predetermine a production schedule solution of minimum cost as an optimum solution according to the mathematical programming. After that, the production schedule is artificially corrected in such a manner as to satisfy the actual restraints based on the approximated or simplified restraints, or to give priority to a specific product unconditionally for the reason of sales without regard to the cost. These artificial corrections are monitored and evaluated, and if not realizable, an alarm is issued against them, while if realizable, the effect on the minimum cost obtained as the optimum solution of mathematical programming is calculated and the result is displayed. The conventional technique (1) described above is a method for calculating and displaying the effect that an artificial operation of a production scheduling causing superfluous parts has on the minimum cost obtained as an optimum solution of the mathematical programming, but has no function of providing a procedure for eliminating actual superfluous parts.
The conventional technique (2) described above, on the other hand, is a process planning evaluation system in which process planning data and incoming order prediction data are prepared from the achievements of the previous year, the amounts of a product in stock and a product out of stock are determined by simulating such data. The process planning is quantitatively evaluated by converting the amount of the product in stock and the product out of stock into a cost according to a predetermined formula. Then, the operator checks the figures, and if necessary, corrects the process planning. In the conventional technique (2), therefore, a superfluous product in stock is determined by simulation and converted into a cost and displayed sometimes to request the correction of the process planning, but no procedure is provided for eliminating actual superfluous parts.
In correcting a production plan upward according to the conventional method, parts newly required, if any, are not purchased, but superfluous parts in stock are checked for and if there are any, they are delivered out to reduce the stock. The conventional method, however, is not intended to positively search the superfluous parts for automatically determining a product that can be manufactured, select a proper one out of a plurality of products that can be manufactured and add it to the production plan.
Also, even when superfluous parts are eliminated by the upward correction of the production planning, a subsequent change in the production plan for eliminating deficient parts may generate superfluous parts anew. In the case where a new production plan is added by combining superfluous parts and newly acquired parts, for example, a subsequent change of the line from a product using deficient parts to a product using no deficient parts for eliminating the deficient parts converts the otherwise superfluous parts into required parts, with the result that the newly acquired parts become superfluous parts.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a production planning system in which the procedure for reducing superfluous parts can be carried out in a production plan.
More specifically, there is provided a production planning system in which deficient parts are calculated first of all and eliminated by cancelling a part of a production plan. Then, the whole truth of the superfluous parts is revealed, the products using the superfluous parts are searched for a proper product, and a production plan for the particular product is added as a new production plan. This series of procedure is executed to eliminate the superfluous parts.
In order to achieve the above-mentioned object, the present invention is based on the following concept:
(1) A production planning system includes a deficient part calculation section for collating the required amount of material resources calculated from the production planning information and the parts list information with the parts in-stock information and the parts warehousing schedule information thereby to calculate the type and quantity of parts expected to run short, thereby making clear the current situation of deficient parts.
(2) A production planning system includes a deficient parts elimination section for checking and listing the products using the above-mentioned deficient parts, comparing the sufficiency or deficiency of other parts used by such products sequentially, selectively eliminating the products containing deficient parts in the descending order of the number of deficient parts, and repeatedly deleting the particular products from the production plan until all deficient part are eliminated, whereby the current production plan is improved to a feasible production plan.
As a method of eliminating deficient parts, the deficient parts can be newly purchased as long as the requirement for the acquisition lead time is met by the plan involved.
(3) A production planning system includes a superfluous parts calculation section for collating the required amount of material resources recalculated from the feasible production plan information and the parts list information with the parts warehousing schedule information containing the parts in-stock information and the new parts purchase information thereby to calculate the type and quantity of the parts which are expected to be superfluous, whereby the current situation of superfluous parts is revealed. The superfluous parts situation revealed by this procedure also includes the superfluous parts newly generated by cancellation of the plan for the products containing deficient parts.
(4) A production planning system includes a superfluous parts elimination section for checking and listing the products using the above-mentioned superfluous parts, sequentially proposing for comparison the superfluity or deficiency of the other parts used by each product, selecting the plans which can be accomplished with the superfluous parts alone and which can thus eliminate as many superfluous parts as possible, in the descending order of the number of such superfluous parts, and adding such a plan to the production plan and repeatedly carrying out a similar process until the superfluous parts are eliminated as far as possible, whereby the production plan can maximize the profits in the sense
Arai Yoshinao
Enomoto Mitsuhiro
Kato Yoshihisa
Tamaki Kenji
Tateishi Jun
Antonelli Terry Stout & Kraus LLP
Beausoleil Robert
Hitachi , Ltd.
Vo Tim
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