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-1 . The grinding head was actuated by two-axes (X, Z) drives, the wheel center point was calculated numerically by using Newton-Raphson method. This system was suitable for grinding micro aspherical surfaces and a form accuracy of less than 0.1 µmP-V was obtained. The improvement of the form accuracy will be required because the specifications of...
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... improvement of the form accuracy will be required because the specifications of micro lenses become more and more strict in future. However, the shape correction cannot be done satisfactorily, because the wheel wear is not even and the grinding point on the wheel moves as shown in Figure 2. In this case, wheel truing is necessary and it will increase the non-processing time. ...
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Citations
... In [268] a grinding method to manufacture moulding tools for manufacturing micro lenses with aspherical surfaces was presented. The authors were able to manufacture a moulding tool with a diameter of 3 mm [268]. ...
... In [268] a grinding method to manufacture moulding tools for manufacturing micro lenses with aspherical surfaces was presented. The authors were able to manufacture a moulding tool with a diameter of 3 mm [268]. ...
The demand for miniaturized products and functionalized parts
is increasing, and many such products are made of hard and brittle
materials machined by abrasive processes. The first part of this keynote
paper is dedicated to a discussion of micro parts and micro structures
machined - at least in part - by abrasive processes, followed by a
discussion of the associated abrasive processes. The strengths and
limitations of these processes, among which include dicing, micro
grinding, micro abrasive blasting, and vibration and magnet field
assisted finishing are discussed. The paper concludes with a discussion
of future trends in the field.
... As any eccentricity would cause deterioration of the form accuracy, the active arc nose centre of the grinding wheel needs to be located on the rotational axis of the B-axis in this procedure. Yamamoto et al. [17,24]. developed another grinding method with three simultaneous-motioned linear axes (X, Y, Z) and a 45°-inclined grinding spindle in the Y-Z plane. ...
A novel approach of three-linear-axis ultra-precision grinding with wheel path generation, tool interference checking and profile compensation is proposed and systematically investigated for fabricating aspheric surfaces. The performance of the proposed techniques is evaluated by grinding an aspheric mould insert on bindless tungsten carbide. The experimental results demonstrate that the profile error can be reduced to 0.1 μm or a lower value in peak to valley (PV) after two compensation cycles. The on-machine measurement results show agreement with the off-machine measurement results when commercially available profilometers are employed. The study confirms the feasibility of the proposed wheel path determination method and the developed profile compensation approach. A mirror surface with roughness less than 8 nm in Sa is achieved.
Precision injection molding is the most efficient mass production technology for manufacturing plastic optics. Applications of plastic optics in field of imaging, illumination, and concentration demonstrate a variety of complex surface forms, developing from conventional plano and spherical surfaces to aspheric and freeform surfaces. It requires high optical quality with high form accuracy and lower residual stresses, which challenges both optical tool inserts machining and precision injection molding process. The present paper reviews recent progress in mold tool machining and precision injection molding, with more emphasis on precision injection molding. The challenges and future development trend are also discussed.
Microaspherical and freeform optics of hard and brittle materials have been more and more widely used in aerospace, optical system, and digital products with the rapid development of science and technology. The wheel normal grinding has an important practical significance for the manufacture of these microaspherical and freeform optical surfaces because not only the interference between grinding wheel and microsurface can be overcome but also the tool geometry errors can be avoided to transfer into the ground surface. In this paper, the kinematics and surface formation in wheel normal grinding process were presented firstly. Then, for hard and brittle materials, the maximum uncut chip thickness and ductile/brittle regime have been addressed by analysis of grinding mode and calculation of ductile/brittle transition critical depths. Special attention has been given to the condition for generating a ductile mode response on the ground surface in wheel normal grinding process. Finally, the aspherical surfaces of BK7, ZERODUR, and binderless WC were ground by wheel normal grinding. The surface roughness Ra was 8.5, 6.6, and 7.4 nm, respectively, and the form error (PV) of BK7 and binderless WC was less than 0.3 μm, while that of ZERODUR was less than 0.5 μm.
The target of this paper is the evaluation of process kinematics in ultra-precision grinding for the manufacturing of typical precision glass moulds (diameter 5 mm to 20 mm) with respect to part quality (form accuracy, surface roughness), machining time and process stability. This is discussed exemplary for two specific grinding kinematics by comparison of experimental results regarding achievable figure accuracy and surface finish.
Ultra-precision grinding is primarily used to generate high quality and functional parts usually made from hard and difficult to machine materials. The objective of ultra-precision grinding is to generate parts with high surface finish, high form accuracy and surface integrity for the electronic and optical industries as well as for astronomical applications. This keynote paper introduces general aspects of ultra-precision grinding techniques and point out the essential features of ultra-precision grinding. In particular, the keynote paper reviews the state-of-the-art regarding applied grinding tools, ultra-precision machine tools and grinding processes. Finally, selected examples of advanced ultra-precision grinding processes are presented.
