Photovoltaic systems generally consist of six individual components: the solar PV array, a charge controller, a battery bank, an inverter, a utility meter, and an electric grid. A review of published literature reveals that that micro structure arrays can enhance the optical performance of photovoltaic components such as solar light guide plates, which are widely used in the fields of bionics, biomedicine, aerospace and defense etc. Consequently, the influence of the size and distribution of micro structure arrays on optical performance has attracted much attention. At present machining methods for such micro structure arrays are mainly divided into mechanical machining and non-mechanical machining methods. The ultra-precision machining technologies applied to machining micro structures usually by means of fast tool servo technology (FTS), slow tool servo technology (STS), ultra-precision milling, grinding or fly cutting. Resent publications have shown that the FTS is an effective method for complex micro structure arrays machining due to the fact that, in FTS, the workpiece is attached on the spindle and rotates while the tool is installed on the FTS tool holder. Unfortunately, due to machine tools lack of linear axis, this approach is unable to machine straight-groove-type micro structure arrays.
Overall, optical micro structure arrays, with regular geometrical morphology such as micro groove array, pyramid array, triangular pyramid array, etc., are widely used in optical components due to their unique optical properties. The machining of these micro structure arrays needs the cooperation of the multi linear axes of precision machine tools, while the lack of certain linear axis (e.g. Y-axis) limits the machining of such micro structure arrays. To address this, Shenzhen University researchers: Mr. Jiankai Jiang, Mr. Tong Luo, Professor Guoqing Zhang and Dr.Yuqi Dai proposed a novel machining system, by which the machining of straight-groove-type micro structure arrays such as pyramid array and triangular pyramids could be realized in a commercial machine tool containing only X, Z, and C axes. Their work is currently published in the research Journal of Materials Processing Tech.
To begin with, the researchers first established a mathematical model for the tool trajectory linearization. The team then designed the machining scheme and undertook cutting experiments of micro groove array, pyramid array and triangular pyramid array. Finally, the machined and designed morphology of the micro structure arrays were compared and analyzed.
The authors reported that both theoretical and experimental test revealed that the machined and designed morphology of the micro structure arrays matched well, the root mean square (RMS) value of the form error of micro groove array, pyramid array and triangular pyramid array were below 1 μm. Further, their works confirmed that the proposed OFCS is an effective machining method for the straight-groove-type micro structure arrays. In fact, it was seen to provide a technical solution for machining straight-groove-type micro structure array in the absence of linear axis of ultra-precision machine tools, also provides theoretical reference for other machining of complex micro structure arrays.
In summary, the study proposed a novel offset-fly-cutting-servo (OFCS) system to machine straight-groove-type micro structure arrays. The developed approach was achieved through the combination of slow tool servo (STS) and fly cutting. Remarkably, the empirical results published herewith were seen to be in good agreement with the simulation results. In fact, the machined micro groove array, micro pyramid array and micro triangular pyramid array had micron-level form accuracy. In a statement to Advances in Engineering, Professor Guoqing Zhang mentioned that compared with the traditional FTS and STS, the OFCS could machine large area micro structure arrays, which are not limited by tool feed frequency.
Jiankai Jiang, Tong Luo, Guoqing Zhang, Yuqi Dai. Novel tool offset fly cutting straight-groove-type micro structure arrays. Journal of Materials Processing Tech. Volume 288 (2021) 116900.