Relationship between dynamic characteristics of air film of aerostatic spindle and mid-frequency of surface topography

Abstract

The dynamic characteristics of the gas film of an aerostatic spindle primary affect workpiece waviness in ultra-precision machining. To improve the machining accuracy of the machine tool and provide a firm theoretical basis for the design of an aerostatic spindle, a simulation model combining transient computational fluid dynamics (CFD) analysis and transient dynamic analysis is established in this study to investigate the dynamic characteristics of the spindle under unstable operating conditions. Based on a large eddy simulation, a three-dimensional flow model of an air film in an aerostatic spindle is established. The simulation results show that the gas flow in the throttle chamber is turbulent, and that complex vortices are formed. Using dynamic grid modeling technology, a CFD numerical model for the unsteady calculation of the spindle is established, and the dynamic characteristics of the gas film are obtained. A transient dynamic simulation model of an aerostatic spindle is established, and the effect of the nonlinear dynamic characteristics of the gas film on the spindle displacement response is investigated. Subsequently, a surface morphology prediction model is established. Results show that film fluctuation significantly affects the dynamic characteristics of the spindle and subsequently affects the generation of surface ripples on the workpiece.

Keywords

Dynamic characteristics / Aerostatic spindle / Surface formation / Ultra-precision flying cutting

References

[1] Chen D, Huo C, Cui X, et al. Investigation the gas film in micro scale induced error on the performance of the aerostatic spindle in ultra-precision machining. Mech Syst Signal Pr, 2018, 105: 488-501.

[2] Cui H, Lei D, Zhang X, et al. Measurement and analysis of the radial motion error of aerostatic ultra-precision spindle. Measurement, 2019, 137: 624-635.

[3] Cai T, Zhang M, Zhu Y, et al. Error modeling and analysis of an ultra-precision stage with an aerostatic bearing. J Tsinghua Univ (Sci & Tech), 2011, 51(6): 857-861.

[4] Zhang SJ, To S, Wang HT. A theoretical and experimental investigation into five-DOF dynamic characteristics of an aerostatic bearing spindle in ultra-precision diamond turning. Int J Mach Tool Manu, 2013, 71(8): 1-10.

[5] Chen D, Cui X, Pan R, et al. A prediction model of the surface topography due to the unbalance of the spindle system in ultra-precision fly-cutting machining. Adv Mech Eng, 2018, 10(1): 1-11.

[6] An C, Deng C, Miao J, et al. Investigation on the generation of the waviness errors along feed-direction on flycutting surfaces. Int J Adv Manuf Tech, 2018, 8: 1-9.

[7] Lozano-Duran A, Bae HJ. Error scaling of large-eddy simulation in the outer region of wall-bounded turbulence. J Comput Phys, 2019, 392: 532-555.

[8] Chen X, Han C, Zhu J, et al. Vortex suppression and nano-vibration reduction of aerostatic bearings by arrayed micro-hole restrictors. J Vib Control, 2015, 32(1): 77-78.

[9] Zhu J, Chen H, Chen X. Large eddy simulation of vortex shedding and pressure fluctuation in aerostatic bearings. J FLUID STRUCT, 2013, 40(7): 42-51.

[10] Salkhordeh S, Kimber ML (2019) Full-field dependence on inlet modeling of non-isothermal turbulent jets using validated large eddy simulations. J Fluid Eng-T ASME 141(8).

[11] Abbà A, Bonaventura L, Nini M, et al. Dynamic models for large eddy simulation of compressible flows with a high order DG method. Comput Fluids, 2015, 122: 209-222.

[12] Du J, Zhang G, Liu T, et al. Improvement on load performance of externally pressurized gas journal bearings by opening pressure-equalizing grooves. Tribol Int, 2014, 73(5): 156-166.

[13] Munoa J, Beudaert X, Dombovari Z, et al. Chatter suppression techniques in metal cutting. CIRP Ann-Manuf Techn, 2016, 65(2): 785-808.

[14] Uddin MS, Seah KHW, Li XP, et al. Effect of crystallographic orientation on wear of diamond tools for nano-scale ductile cutting of silicon. WEAR, 2004, 257(7): 751-759.

[15] Wang SJ, To S, Cheung CF. An investigation into material-induced surface roughness in ultra-precision milling. Int J Adv Manuf Tech, 2013, 68(1/4): 607-616.

[16] Zhang SJ, To S. A theoretical and experimental study of surface generation under spindle vibration in ultra-precision raster milling. Int J Mach Tool Manu, 2013, 75(12): 36-45.

[17] Chi FC, Lee WB. A multi-spectrum analysis of surface roughness formation in ultra-precision machining. Precis Eng, 2000, 24(1): 77-87.

[18] Chen G, Sun Y, An C, et al. Measurement and analysis for frequency domain error of ultra-precision spindle in a flycutting machine tool. P I Mech Eng B-J Eng, 2018, 232(9): 1501-1507.

[19] An CH, Zhang Y, Xu Q, et al. Modeling of dynamic characteristic of the aerostatic bearing spindle in an ultra-precision fly cutting machine. Int J Mach Tools Manuf, 2010, 50: 374-385.

[20] Zhang SJ, To S. A theoretical and experimental investigation into multimode tool vibration with surface generation in ultra-precision diamond turning. Int J Mach Tool Manu, 2013, 72(18): 32-36.

[21] Baek DK, Ko TJ, Kim HS. Optimization of feed rate in a face milling operation using a surface roughness model. Int J Mach Tool Manu, 2001, 41(3): 451-462.

[22] Cheung CF, Lee WB. Characterisation of nanosurface generation in single-point diamond turning. Int J Mach Tool Manu, 2001, 41(6): 851-875.

[23] Chen W, Lu L, Yang K, et al. An experimental and theoretical investigation into multimode machine tool vibration with surface generation in flycutting. Proc I Mech E Part B: J Eng Manuf, 2015, 230: 1-6.

[24] Boersma BJ, Lele SK (1999) Large eddy simulation of compressible turbulent jets. In: Center for Turbulence Research, Annual Research Briefs, Stanford University, pp 365–377

[25] Yoshimoto S, Suganuma N, Yagi K, et al. Numerical calculations of pressure distribution in the bearing clearance of circular aerostatic thrust bearings with a single air supply inlet. J Tribol, 2007, 129(2): 384-390.

[26] Chen XD, Zhu JC, Han CS. Dynamic characteristics of ultra-precision aerostatic bearings. Adv Manuf, 2013, 1(1): 82-86.

[27] Khajehzadeh M, Razfar MR. FEM and experimental investigation of cutting force during UAT using multicoated inserts. Adv Manuf Processes, 2015, 30(7): 10

Funding

national natural science foundation of china http://dx.doi.org/10.13039/501100001809(51875005)