ABSTRACT
New methods of computer-aided production control and total quality management are necessary to produce concrete precast elements effectively according to the market requirements and quality assurance demands.
The production of precast tunnel elements makes especially high demands on the product quality, in particular concerning the compliance with geometrical parameters. These quality demands effectively may be fullfilled only by means of process control systems and coupled with them quality assurance and quality management systems. There are described concepts which represent different developement stages of a complex process control system with quality diagnostic and quality prognostic components.
As basis of the automation system are taken the object-orientated process control system PROVBE which had been developed by the Institute IITB Karlsruhe—member of the Fraunhofer Society Germany (FhG)—as process visualization and control system PROVIS and adapted in co-operation of the FhG—IITP Karlsruhe and the Institute of Prefabrication Technology and Construction Weimar Reg. Ass. (IFF) as system PROVBE to the requirements of application in precasting works.
The quality diagnosis is based on the principle, that the supervision of process parameters and parameters of the finished concrete element with regard to assurance of rated values is made possible through on-line data acquisition of relevant process data. The quality diagnosis mostly results only in a “good”- or “bad”- decision on the usability of the produced concrete element. Changes of production conditions which are necessary to eliminate the found quality deficiencies are only possible in off-line mode.
The quality prognosis, however, aims at finding trend changes in the production process by current on-line data acquisition and analysis, detecting and correcting this way creeping parameter deviations in early stages, so that the concrete element representing the final product may be produced in stable quality. Trend changes in the production process are not only due to failures and defects, wear on wearing parts is not avoidable. Therefore a quality prognostic system has to give orders to carry out the prophylactic maintenance and if necessary to displace wearing parts. Necessary corrections in the production process to a certain state are possible in online mode. The prophylactic maintenance ensures the functioning of machinery and plants, so that the flawless production may be formulated as the goal of the application of quality prognostic systems.
