Data processing: generic control systems or specific application – Specific application – apparatus or process – Product assembly or manufacturing
Reexamination Certificate
2002-10-01
2003-12-09
Picard, Leo (Department: 2125)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Product assembly or manufacturing
C700S099000, C700S108000
Reexamination Certificate
active
06662064
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a method and a device for the adaptive control of complex production chains, and to a system for implementing such a method.
In many branches of industry, the production process is subdivided into different production lines, also called production chains. A production chain is the series connection of a number of production machines. Between the machines there are so-called buffers, with which different process speeds of the production machines and short stoppages can be compensated for.
The essential characteristic variable of a buffer is the buffer time, that is to say a time during which a supply of intermediate products is produced, with which a stoppage of a machine can be bridged without the production line coming to a standstill. There are guidelines from the manufacturer of the production plant for defining the respective buffer time.
A desired buffer time set in accordance with such predefinitions does not in any way have to be the optimum buffer time, however, particularly with regard to the production costs, which are influenced to quite a significant extent by production losses. The optimum buffer time compensates for faults in the respectively preceding machine, so that there is no loss of production. Optimum buffer times cannot be achieved with fixed time predefinitions, since influences such as machine age or quality of the material processed are not taken into account.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a method, a data processing device, and a system for adaptive control of complex production chains that overcome the hereinafore-mentioned disadvantages of the heretofore-known methods, devices, and systems of this general type and that adaptively control a production chain by automatically optimizing the desired buffer times of production chains.
With the foregoing and other objects in view, there is provided, in accordance with the invention, a method of controlling a discrete production process. Such discrete production processes typically utilize a series of production steps to process a product. Each of the steps use a respective machine to produce a respective intermediate product. Respective buffer times are defined for each step. Each of the buffer times has a long enough duration that at least one of the number of machines is able to continue to operate throughout a failure of one of the machines of a preceding production step by processing a stock of intermediate products. The previous intermediate products are stored in a buffer during production in case of a failure of a previous machine. The first step of the method is acquiring production data for each machine. The next step is cyclically calculating statistically averaged repair times with an MTTR calculator from the production data. The next step is calculating desired buffer times with a T
P
calculator from the statistically averaged repair times. The next step is feeding the desired buffer times to a device for controlling the production process.
With the objects of the invention in view, there is also provided a data processing device working in conjunction with a production system for processing products. The production system includes a desired-value memory and a series of production stations. Each of the production stations have a respective machine performing a respective step to produce a respective intermediate product and have a respective buffer time stored in the desired-value memory. At least one of the machines can continue to operate throughout a failure of one of the machines of a preceding production step by processing a stock of intermediate products corresponding to the associated buffer time and stored in a buffer. The data processing device automatically optimizes the buffer times and includes a data server, a production database, an MTTR database, a production data acquisition device, an MTTR calculator, and a T
P
calculator. The data server stores data including production data and fault event data. The production data acquisition device can access the data in the data server, has a data input for receiving additional fault event data, registers stoppage times of the machines, and stores the stoppage times of the machines in the production database. The MTTR calculator accesses the production database, calculates MTTR characteristic values from the stoppage times, and stores the MTTR characteristic values in the MTTR database. The T
P
calculator accesses the MTTR database, calculates the buffer times from the MTTR characteristic values using an assessment model, and stores the buffer times in the desired-value memory.
With the objects of the invention in view, there is also provided a production system which combines the production system described above with the data processing device described above.
By using the invention in a production chain, automated optimization of the buffer times is achieved during its entire life cycle.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a method, a data processing device, and a system for adaptive control of complex production chains, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
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Chen, F. F. et al.: “Analytical Modeling and Analysis of Flexible Manufacturing Systems Considering System Component Failure/Repair Rates”, Journal of Manufacturing Systems, vol. 15, No. 3, 1996, pp. 143-154.
Milanovic Raiko
Vollmar Gerhard
ABB Research Ltd.
Greenberg Laurence A.
Locher Ralph E.
Picard Leo
Stemer Werner H.
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