The trend in the optic industry shows, that it is increasingly important to be able to manufacture complex lens geometries on a high level of precision. From a certain limit on the required shape accuracy of optical workpieces, the processing is changed from the two-dimensional to point-shaped processing. It is very important that the process is as stable as possible during the in point-shaped processing. To ensure stability, usually only one process parameter is varied during processing. It is common that this parameter is the feed rate, which corresponds to the dwell time.
In the research project ArenA-FOi (Application-oriented analysis of resource-saving and energy-efficient design of industrial facilities for the optical industry), a touching procedure is used in the point-attack, and in this case a close look is made as to whether a change of several process parameters is meaningful during a processing. The ADAPT tool in size R20 from Satisloh AG is used, which is also available for purchase. The behavior of the tool is tested under constant conditions in the MCP 250 CNC by OptoTech GmbH. A series of experiments should enable the TIF (tool influence function) to be determined using three variable parameters. Furthermore, the maximum error frequency that can be processed is calculated as an example for one parameter set and serves as an outlook for further investigations. The test results serve as the basic for the later removal simulation, which must be able to deal with a variable TIF. This topic has already been successfully implemented in another research project of the Institute for Precision Manufacturing and High-Frequency Technology (IPH) and thus this algorithm can be used.
The next step is the useful implementation of the collected knowledge. The TIF must be selected on the basis of the measured data. It is important to know the error frequencies to select the optimal TIF. Thus, it is possible to compare the simulated results with real measurement data and to carry out a revision. From this point onwards, it is possible to evaluate the potential of this approach, and in the ideal case it will be further researched and later found in the production.
The trend in the optic industry shows, that it is increasingly important to be able to manufacture complex lens geometries on a high level of precision. The most interesting geometries are aspheric and free-form surfaces, which can only be produced with a huge time and cost effort until today. With these geometries it is possible to replace a number of spherical lens with just one aspheric or one free-form lens. As a result, installation space and weight are reduced, as well as scarce resources can be protected.
The goal of the research project ArenA-FOi (Application-oriented analysis of resource-saving and energy-efficient design of industrial facilities for the optical industry) is to create a new processing machine for manufacturing high precision optics. The primary kinematic system of the new machine is a Hexapod, which stands for high precision positioning and repeated accuracy. In addition, a Hexapod system is characterized by high stiffness and the reduction of mass, compared to existing machines. In the first phase of the project, the focus is on the machine concept, based on the required product range. Furthermore, it should be possible to create spiral and raster tool-paths for the process of machining. Especially, the raster tool-path is only applicable by a high radius of curvature which is limited by the maximum inclination of the Hexapod. If the result of the machine concept shows that an additional axis is needed, this axis must ensure synchronous control. Up to now, the processing of aspherical lenses is carried out by using the dwell time and vertical machining for the spherical best fit geometry. In this research project, we want to machine surface normal at every single point of the entries process and we also expect a quality improvement.
In this paper, only the project concept and the project's first phase — the plant construction and the development of aspherical surfaces — are discussed.
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