Influence of robotic structural deformation on bonnet polishing removal function
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摘要: 基于气囊抛光技术和工业机器人平台开发光学元件精密抛光系统,既能满足光学元件快速抛光环节的高效率和高精度的要求,又可以降低开发成本,是极具潜力的抛光设备开发方案。气囊抛光具有稳定的且确定的材料去除特性,通常要求抛光斑稳定性在90%左右。针对机器人气囊抛光系统在多步离散进动抛光过程中机器人末端刚度对气囊抛光稳定性的影响展开研究,通过建立机器人末端刚度矩阵,获得机器人末端变形;基于Preston理论,建立含变形误差的气囊抛光去除函数。最后设计4步离散定点抛光实验验证机器人气囊抛光系统稳定性。根据结果可知抛光斑在XY截面轮廓线上皆呈类高斯形状,且XY截面轮廓线基本一致,具有比较好的重合度;对比不同抛光位置的截面轮廓线,其相对误差小于5%,由此可验证机器人气囊抛光系统在离散进动抛光时具有较好的稳定性。Abstract: Precision polishing system for opticals based on bonnet polishing technology and industrial robot can not only meet the requirements of high efficiency and precision of rapid polishing, but also reduce the development cost, thus it is a potential development solution for polishing. Bonnet polishing requires stable and deterministic material removal characteristics, and the stability of polishing spot is usually around 90%. The influence of robot stiffness on the stability of robot bonnet polishing system in the process of multi-step discrete precession polishing was studied. The robot end deformation was analyzed by the stiffness matrix, and the removal function of bonnet polishing with deformation error was established based on Preston theory. Finally, a four-step discrete polishing experiment was designed. According to the results, the polishing spot was Gaussian on the xy section contour line, and the xy section contour line was basically the same, with a good coincidence degree. Comparison of the cross-section profiles at different polishing positions indicates, the relative errors are below 5%. The experiment proves that the robot bonnet polishing system has a good stability in discrete precast polishing.
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Key words:
- bonnet polishing /
- industrial robot /
- stiffness matrix /
- removal function /
- polishing experiment
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表 2 机器人末端变形理论计算结果
Table 2. Theoretical calculation results of robot end deformation
four × 90° steps x direction/mm y direction/mm z direction/mm whole deformation/mm 0° 0.1206 0 −0.2710 0.2966 90° 0.1221 0.0003 −0.2778 0.3034 180° 0.1238 0 −0.2846 0.3103 270° 0.1221 −0.0003 −0.2778 0.3034 表 1 机器人4步定点抛光关节转角
Table 1. Robot fixed-point polishing joint angle in four steps
four × 90°steps $ {\theta }_{1}$/(°) $ {\theta }_{2}$/(°) $ {\theta }_{3}$/(°) $ {\theta }_{4}$/(°) $ {\theta }_{5}$/(°) $ {\theta }_{6}$/(°) 0° 0 32.36 14.80 0 22.84 0 90° −4.41 39.06 3.48 25.65 51.99 −21.17 180° 0 45.76 −8.29 0 72.53 0 270° 4.41 39.06 3.48 −25.65 51.99 21.17 表 3 气囊抛光有限元仿真设定条件
Table 3. Setting conditions of bonnet polishing finite element simulation
bonnet radius/mm tool offset/mm precession angle/(°) inner pressure/MPa rotation speed/(r·m−1) 80 0.2,0.6,1 20 0.25 1000 表 4 接触压力数值拟合结果
Table 4. Numerical fitting results of contact pressure
maximum stress/MPa standard deviation $\sigma $ modification coefficient $\varphi $ 1.708 2 1.231 5 0.175 5 表 5 气囊抛光实验参数
Table 5. Bonnet polishing experiment parameters
bonnet radius/
mmprecession
stepstool offset/
mmprecession
angle/(°)inner pressure/
MParotational
speed/(r·min−1)dwell time
(each step)/s80 4 0.6 20 0.25 500 20 表 6 静态压力测量结果
Table 6. Static pressure measurement results
(N) experimental group F (1st step/0°) F (2nd step/90°) F (3rd step/180°) F (4th step/270°) 1st 105.5 108.7 113.6 105.1 2nd 101.2 106.1 116.6 116.8 3rd 91.4 94.2 103.2 89.3 mean 99.4 103.1 111.1 103.79 表 7 抛光区域去除深度和相对误差值
Table 7. Polished area removal depth and relative error value
experimental group removal depth/μm relative error/% spot 1 13.249 0 spot 2 13.599 2.64 spot 3 13.864 4.64 spot 4 13.845 4.50 -
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