Einfluß von hohem allseitigem Druck auf die α/γ-Umwandlung von Eisen-Chrom-Legierungen unter besonderer Berücksichtigung der Druckmessung bei hohen Temperaturen

Untersuchungen über den Einfluß von allseitigen Drücken bis 25 kbar auf das Gleichgewicht zwischen α- und γ-Phase in Legierungen des Eisens mit 5 bis 15% Cr unter Anwendung der Differential-Wärmeleitfähigkeits-Analyse als Meßverfahren und von Reineisen als Druck-Temperatur-Eichstoff. Isobarenschaubild des Zweistoffsystems.     

Reaktive klebstoffe

Adhesives based on polychloroprene, natural rubber or polyurethanes are frequently used in practice with an addition of polyisocyanates as ?reactive adhesives”? in order to improve the strength and durability of the bonds. It is investigated wether the polyisocyanate increases the cohesion of the high polymer adhesive base by a network formed by a polyisocyanate-humidity reaction product, i. e. mere mechanically or by real chemical bonds. It is stated that chemical bonds are formed. The increase of cohesion is strongly influenced by the type of polyisocyanate added. The adhesion to rubber materials is also promoted by chemical reactions at the interface.     

Manufacturing of dies from hardened tool steels by 3-axis micromilling

In this paper the results of an experimental investigation to analyze the machinability of a hardened, carbide-rich cold-work tool steel 1.2379 (approx. 62 HRC) with coated micro end-milling cutters are discussed. Fundamental experiments were performed to determine a cutting-parameter set, which enables an economic manufacturing of dies by 3-axis micromilling with commercially available cemented-carbide tools. The evaluation of the applicability of different tool types is conducted by analyzing the process forces, the tool wear, the surface quality, the material removal rate, and the entire chip volume. Design of experiments was used to significantly reduce the number of experiments and to model the active and passive forces. Concerning the design of tools for the micromilling of such difficult-to-machine materials, it is shown that cemented-carbide tools with robust cutting edges are applicable for this kind of machining. Furthermore, test microstructures were manufactured with the intention of validating the determined cutting-parameter set in combination with the selected tool types. In addition, the dimension and shape accuracy of the microstructures are analyzed.