Papers by Author: Luis de Leon

Abstract: Novel manufacturing technologies for high-strength structural components of aluminium allow a local modification of material properties to respond to operational demands. Machining and finishing processes for changing material properties like deep rolling or rubbing are to be combined to a single process step. The intention is the controlled adjustment of the component’s properties by the modification of its subsurface. For that purpose the essential understanding of the interaction mechanisms of the basic processes turning, deep rolling and rubbing is necessary. Influences of the tool geometry as well as of the process parameters on the material properties are investigated. The results will be extended by parameter studies within numerical simulations. Thereafter, combinations of the basic processes in process sequences are analyzed to their ability to modify the subsurface properties. In consideration of these results, a prototypic combined turn-rolling tool is developed

Abstract: The wire sawing process is a highly flexible cut-off grinding process. Nowadays it is not only used in its traditional field of application (processing of natural stone) but also in the civil construction industry and for the destruction of metallic structures. In order to extend the knowledge about the process it is one goal of the Institute of Production Engineering and Machine Tools (IFW) of the Leibniz Universität Hannover, Germany, to investigate the cutting mechanisms. These are supposed to be the basis for a tool design taking into account the specific field of application. The results presented within this paper describe an approach to explain the interdependencies of the system and manipulable variables for the wire sawing process. From these interrelationships the cutting mechanisms will be derived.

Abstract: Five-axis-grinding is a process, which merges high surface quality and high shape accuracy for high precision machining of multiple curved surfaces. Until now, characteristic parameters, which describe the interaction of the grinding tool and the workpiece are not available. In the present paper models for the analytical determination of the contact condition for surface normal grinding of double curved surfaces with toric grinding wheels are introduced to evaluate and configure the machining parameters.

Abstract: The need for new cutting tool technologies is driven by the constantly increasing performance of machine tools and the rising market competition. Current research results show that an improved combination of the cutting edge macro- and microgeometry, together with an appropriate substrate and coating, leads to a significant enhancement of cutting tool performance. Furthermore, inappropriate cutting edge microgeometries cause, in addition to the higher production costs, a reduction of the tool life. Hence, it is essential to produce tailored cutting edge microgeometries with high precision and process reliability. This paper presents the influence of brushing process parameters on the size and the form of produced cutting edges of indexable inserts. This leads to a better understanding and higher quality of the cutting edge preparation process by means of abrasive brushes. Furthermore, the process reliability of 5-axes brushing is analyzed. An example of a tool life map presents the significantly enhanced tool performance through cutting edge preparation and its sensitivity towards varying the cutting edge microgeometry.

Abstract: After the grinding process, the cutting edges of cemented carbide milling tools tend to chipping. Chipping has a strong influence on the tool performance. For this reason, the cutting edges are further prepared. Additionally, a cutting edge rounding has an impact on the wear behavior and the process stability. For the cutting edge preparation of milling tools, magnetic finishing is a promising process. This paper describes the process of magnetic finishing. The influencing parameters, i.e. the process time and the distance between the cutting tool and the magnetic disks, are investigated. Furthermore, the effect of magnetic finishing on the tool life is demonstrated using the example of a milling process with titanium.

Abstract: Harder workpiece materials and increased efficiency requirements for grinding processes make the use of super abrasive grinding wheels indispensable. This paper presents newly developed processes for the dressing of super abrasive grinding wheels. The different bond systems of grinding wheels require distinct dressing process. In this paper, dressing processes for metal and vitrified bonded grinding wheels are investigated. It introduces the method of electro contact discharge dressing for the conditioning of metal-bonded, fine-grained multilayer grinding wheels. A description of the essential correlation between dressing parameters and the material removal rate of the bond material is presented. The considered parameters are the dressing voltage, the limitation of the dressing current and the feed as well as the infeed of the electrode. For the grinding of functional microgroove structures, multiroof profiles with microscopic tip geometries are dressed onto the grinding wheel. For this, a profile roller in combination with a special shifting strategy is applied on finegrained vitrified bonded grinding wheels.