Abstract
Compound sinusoidal grid surface with nanometric finish plays a significant role in modern systems and precision calibrator, which can make the systems smaller, the system structure more simple, reduce the cost, and promote the performance of the systems, but it is difficult to design and fabricate by traditional methods. In this paper, a compound freeform surface constructed by a paraboloidal base surface and sinusoidal grid feature surface is designed and machined by slow tool servo (STS) assisted with single point diamond turning (SPDT). A novel combination of the constant angle and constant arc-length method is presented to optimize the cutting tool path. The machining error prediction model is analyzed for fabricating the compound sinusoidal grid surface. A compound sinusoidal grid surface with 0.03 mm amplitude and period of 4 is designed and cutting process is simulated by use of MATLAB software, machining experiment is done on ultra-precision machine tool, the surface profile and topography are measured by Taylor Hobson and Keyence VR-3200, respectively. After dealing with the measurement data of compound freeform surface, form accuracy 4.25 μm in Peak Village value (PV), and surface roughness 89 nm in Ra are obtained for the machined surface. From the theoretical analysis and experimental results, it can be seen that the proposed method is a reasonable choice for fabricating the compound sinusoidal grid surface.
Highlights
When compared with traditional elements, compound freeform surface elements can obviously make the systems smaller, make the system structure much simpler, reduce the cost, and promote the performance of the systems, and it has drawn more attention in recent years [1,2]
Ying Cheng et al manufactured an off-axis optical reflective integrator by ultra-precision machining, the advancement in this study is to reduce the stepwise discontinuity among the facets to make it applicable for turning, and the off-axis optical reflective integrator is more simple in structure and smaller in size when compared with existing refractive integrators, and simulations and experiments show that above 90% of illumination uniformity can be achieved using this new design [6]
Two different ultra-precision manufacturing methods for off-axis parabolic mirror with single point diamond turning are analyzed and compared by Shijun Ji et al, the two methods are that turning the cylindrical blank by revolving around the axis of the parabolic surface and revolving around the axis of cylindrical surface, besides, the kinematic analyses of two linear axes (X, Z) are studied, the tool path generation and installation errors are analyzed under two different conditions
Summary
When compared with traditional elements, compound freeform surface elements can obviously make the systems smaller, make the system structure much simpler, reduce the cost, and promote the performance of the systems, and it has drawn more attention in recent years [1,2]. Reducing the ratio of sag height to diameter, the cutting path is designed by the coordinate transform They machined the off-axis aspheric mirrors, and fabricated freeform prisms to prove that the proposed method works well for complex surfaces [7]. The cylindrical coordinate micromachining method for ultra-precision cutting of sinusoidal surfaces was studied by Xiaodong Zhang et al, a three-axis turning machine is used and a spiral curve NC path is adopted, they proposed a method to optimize the tool geometry and to simulate the cutting process, a sinusoidal surface with 5.54 nm in
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