Cezary Grabowik

The method of knowledge representation for a CAPP system

Abstract This paper presents a method of representation of the knowledge about the body construction and technology in an expert system that aids the process of designing the machining technology of bodies. The proposed method of object knowledge representation allows recording the technological knowledge acquired from experts. An example of knowledge notation using the Object Pascal language is presented.

Integration production planning and scheduling systems for determination of transitional phases in repetitive production

In the process of multiassortment repetitive production planning the designation of operating system parameters for the steady state (in which after the last operation the return to the first operation in the sequence of productive resources occurs) is required. The length of steady state of the system is determined by the work of the critical resource. Determination of resources sequence for the steady state gives possibility to determine the processing times for processes in the system without taking into account the transitional phases. During the execution of this type of production, in addition to the phase in which production takes place in the steady state, transition phases connected with starting (start-up phase) and finishing work in the system (cease phase), and the phases associated with the changes in ongoing sequences in steady states can be distinguished. The article presents the problem of estimating the duration of the start-up phase and the cease phase in the concurrent multiassortment production systems, in which access to the resources is regulated by the local dispatching rules. A method and a procedure of creating a schedule for the transition phases using the integration between the systems of production planning and scheduling is presented. The demonstrated approach is illustrated with the examples using KbRS and SWZ systems.

Object-oriented models in an integration of CAD/CAPP/CAP systems

In this paper some aspects of CAD/CAPP/CAP systems integration process are described. Moreover, the structure of an integrated environment, which is an answer to this kind of integration problem is shown. Main elements of this environment are technological knowledge base - TKB and scheduling knowledge base - SKB. The foundation for building these knowledge bases was application of object methods in processes of technological and scheduling knowledge representation. In the paper both models it means the object model of technological knowledge representation and scheduling knowledge representation are discussed in details.

The New Approach to Design Features Identification

In this paper a new solution for design features identification is show. The proposed method is based on manual arbitral identification of the potential design features. Application of this method allows identifying a set of design features which can be used for a design modelling in CAD system. As a result of application of the proposed method a user is able to identify the set of design features. This set can be next applied in the process of design production preparation subsystem formation at the stage of design feature library creation.

The Concrete Casting Matrixes Inserts Design Preparation Based on the Master Models

Currently industrial needs exceed traditional design approach solutions. To satisfy that need designer have to deal with mutually exclusive restrictions. The solution to this problemis to maintain these restrictions with proper methodthat guarantees right result. The concrete casting matrixes are not only transits beauty and art but they have also important technical sense in final product. The master model represents the final product a concrete sidewalk brick which have specified form of the top surface. This special structure of the top surface helps drain water off the brick in order to maintain proper griping properties of it after it rains. As soon as the master model wasscannedit was necessary to change outer border line of 3D model because themaster model appeared to be a little bit bigger than the original one. Finally the 3D model it is the outer border line and its geometry were modified in order to keep the original model functionality. All modifications were done with application of reverse engineering and CAD/CAM software.

The hybrid method of knowledge representation in a CAPP knowledge based system

In this paper the hybrid method of manufacturing knowledge representation in the CAPP knowledge based system is presented. In the presented solution the manufacturing knowledge as well as the product design is represented by means of the object method. This paper shows only results obtained at the object design stage (OOD). Currently the scope of decision problems solved by proposed system is limited to axi---symmetric products, but basis on the achievements to date it is thought to develop this system in order to widen the subjected products group. Moreover the detailed description of the inference engine of the CAPP system is given. In the inference engine the two groups of rules were distinguished. In the paper content the examples for each group of rules are shown.

The Graph Representation of Multivariant and Complex Processes for Production Scheduling

The paper presents a solution useful for production scheduling in the context of the constraints arising from the complexity of the structures of realized processes and possibilities of use variants of their implementation. The proposed method uses both activity on arc and activity on node types of graph for describing multivariant processes. Representation of complex (composed) structures the AND-OR graphs are used that combines both conjunction and disjunction relations between nodes.

Predictive - Reactive Strategy for Real Time Scheduling of Manufacturing Systems

In this paper a solution of soft real time scheduling in manufacturing systems is presented. The basic requirements of scheduling as a real time system are discussed. The proposed rescheduling method uses predictive-reactive strategy and multi thread searching approach with rule-based heuristics, meta-heuristics and random modules.

Estimation of Reliability Characteristics in a Production Scheduling Model with Failures and Time-Changing Parameters Described by Gamma and Exponential Distributions

In the paper a classical model of failures is considered in that successive failure-free times are supposed to have Gamma distributions and are followed by exponentially distributed times of repairs. It is assumed that parameters of these distributions, in general, change with time. Basing on information about the number of failures and failure-free times in a number of periods of the same duration in the past, three different methods of estimation unknown parameters of the model are proposed. Next, predictions of the most important reliability characteristics are found.

A Survey on Capp Systems Development Methods

Process planning is one of the most important links in planning of the manufacturing system functioning, it coordinates and integrates processes planners, designers and economists intentions. The main goal to reach during the process planning phase is to determine the process plan structure it is manufacturing operations and cuts which have to be applied in order to transform given semifinished product into a product with the strict determined design and properties. Simultaneously process planers strive for working out such a process plan which satisfies criteria of the lowest manufacturing cost and labour consumption taking into account current accessibility of manufacturing resources. Process planning is still one of the most difficult, complex and time consuming process planner activities. Traditionally the process plan is designed with so-called manual method. During process planning with this method a process planner is forced to analyse the sequence of manufacturing cuts and operations in the process plan structure and also to analyse alternative processes taking into consideration achieving as low as possible unit manufacturing cost. In this case the process plan quality in principle depends exclusively on process planner knowledge and skills. Taking into account above the methods of process planning functions automation are searched. This goal can be reached by application of computer tools. Computer methods of process planning went through the long evolution process and their development is characterized by the following features: decreasing of process planner participation in the planning of the base structure of process plan, broad application of technological databases, broad application of technological knowledge bases, and possibilities of cooperation with commercial CAD/CAM/CAE systems [1,. In this paper the detailed information on methods of computer aided process planning are given. The variant, semi generative and generative methods are discussed. The main merits and drawbacks for each method are shown.