Doctoral theses

Production processes of the forging industry are defined by a multitude of factors. While in the past, technological product quality has been the major goal of improvement efforts, to an increasing degree it is sided with a high logistical performance. However, in the utilisation planning of heaters, a sub-process of heat treatment, there still is often only a markedly insufficient technological-logistical process quality achieved. Relevant problems in this context are – amongst others – the changing of order sequences, the multitude of technological restrictions and the deficient knowledge about technological and logistical interdependencies. For a well-balanced positioning between the compliance with technological restrictions and logistical aims, a method for an automated selection and combination of the evaluated orders into charges and utilization programs is needed. Within this book, such a solution concept for supporting the utilisation planning of heat treatment systems is described. The developed methods of order selection, charge combination and heaters assignment, which are based on the fuzzy-logic, represent the interdependencies between technical and logistical objectives of the utilisation planning, choose suitable orders for the heat treatment, support the combination of charges and assignment programs and offer the saving of specific planning knowledge.

forging industry, heaters utilisation planning, fuzzy-logic, order selection, charge combination

In the context of increasing economic networking more and more companies shift production volumes to foreign locations. However, high return displacement rates show that many companies fail here. The design of the product has a causal influence on the production and therefore on the success of this internationalization. In the present work a method to design internationalization driven product structures will be described. Aims are low product complexity and a customized distribution of know-how. To implement these aims design guidelines are defined, which are assessable using a performance measurement system. An integrated product model and a catalog of options for action assist in the analysis and design. This product structures can be created in an iterative process, which form a basis for successful internationalization.

product structuring, product design, product model, globalization, internationalization

Warm forming of steel is for a limited range of work piece geometries an economic and ecologic alternative to the conventional hot and cold forging technology. Up to now warm forming is predominantly common for rotation symmetric parts. Within the scope of this paper a process chain for closed-die warm forming of long flat pieces has been derived and investigated on the basis of the forming stages of a steering link. The experiments have been performed on a conventional hot forging press. Only a graphite coating machine has been used additionally. It has been verified that long flat pieces made of steel can be warm forged using a preforming operation by bending or drawing out in the die. A material utilisation of 80 % and IT-tolerances lower than IT 12 for width and length have been achieved. Based on FE-simulations it has been shown that, using two preforming operations by bending or drawing out in the die, preforms with a straight, in one plane bent and in two planes bent longitudinal axis can be produced.

bulk metal forming, warm forming, long parts

Various companies implement lean production systems to realize hidden technological and economical potentials. Due to the extensive and long-lasting acquisition of production system knowledge, the implementation of an individualized production system requires comprehensive human and financial resources. In contrary to huge enterprises, respective means are not at the disposal of small and medium sized companies e. g. of the die and mold making industry. This article presents an innovative approach to formalize production system knowledge in an expert system. The system is designed to fit the needs of the die and mold making industry and consists of an ontology for knowledge representation as well as an industry-sector-specific knowledge base. Furthermore, rules for automated knowledge base adaptation are derived using data mining algorithms. Case studies show that the expert system is applicable for systematic and company specific lean-method identification and implementation.

production system, lean production, expert system, knowledge management, data mining

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