1 / 23

Libor Švéda 1 , Martina Landová 2 , Martin Míka 2 ,

Glass thermal formation - experiment vs. simulation. Libor Švéda 1 , Martina Landová 2 , Martin Míka 2 , Ladislav Pína 1 , Radka Havlíková 1 , Veronika Semencová 3 KFE FJFI ČVUT VŠCHT Praha Rigaku Innovative Technologies Europe s.r.o. Motivation

kemp
Download Presentation

Libor Švéda 1 , Martina Landová 2 , Martin Míka 2 ,

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Glass thermal formation - experiment vs. simulation Libor Švéda1, Martina Landová2, Martin Míka2, Ladislav Pína1, Radka Havlíková1, Veronika Semencová3 KFE FJFI ČVUT VŠCHT Praha RigakuInnovative Technologies Europe s.r.o.

  2. Motivation • Glass forming process – brief description • Metrology • Simulations – theory • Simulations – initial results • Perspectives • metrology upgrades • simulation modifications

  3. Motivation • Thermal glass forming as a method how to obtain precise shapes • Precursor to Si wafer forming • Typical applications • glass: • Space x-ray mirrors (large scale, low specific mass, good surface roughness) • Mirrors for catadioptric systems, like the HUD display (large, low cost) • Mirrors for condensors, like the sun heat sources, photomultiplyers etc. (large, low cost) • Silicon • Space x-ray mirrors (excellent surface quality) • Laboratory x-ray mirrors (diffraction imaging, excellent surface quality)

  4. Glass forming process Form defined shaping • Arbitrary shape • High temperature form / mandrel • Contact method – possible surface contamination • „Freefall forming“ • Shape given by physics • Efficient shape modification only by temperature gradients • Non-contact method Oven Oven F G

  5. Metrology - overview • Low precision • In-situ • Process dynamics • Very high precission • On the table • No process dynamics • Possible contamination • Effect of transportation

  6. Metrology – in situprocess dynamics intro

  7. Metrology – in situprocess dynamics curves

  8. Form process parameters prediction

  9. Metrology – in situprofile measurement End of formation After cool down

  10. Metrology – on-the-table

  11. Forming simulations - theory • Heat-up process • Elastic material properties • Forming process • Viscous liquid approximation at given temperature • Strong change of viscosity with temperature!!! • Problem of boundary conditions • Cool-down process • Similar to forming process, except that changing temperature according to the measured temperature decay Temperature gradient? G

  12. Simulations – input parameters • DESAG D263 glass • density: 2.510 g/cm3 • Youngmodulus: 72.9 Mpa • Poisson ratio: 0.209 • thermalcoeff. ofexpansion: 7.2e-6 K-1 • strain point: 529°C • annealing point: 557°C • softening point: 736°C • sample size: • 75x25x0.7 mm • 100 x 100 x 0.4 mm • temperatures used: 540-660°C Dynamic viscosity used

  13. Simulations – viscous liquid ComsolMultiphysics simulations • Viscous liquid at given temperature • Velocity fields at given time • Actual glass profile is obtained by integrating the velocity curves http://www.comsol.com/

  14. Simulations vs. metrologyprocess dynamics 75x25x0.75 mm glass Why?

  15. Simulation vs. metrologyfixed edges

  16. Form process predictions - simulation

  17. Simulation vs. metrologycool down process

  18. Known error sources • Cool down during the image acquisition • Cool down process and corrections for that process • Temperature gradients • No definition of fixed points for forming • Image distortions during the in-situ measurements, no camera fixation • Lighting conditions not well defined • Non existent fast non-contact profilometry (no need to transport over large distances, time gaps)

  19. Perspectives – metrology upgradesin-situ Ronald A. Petrozzo and Stuart W. Singer Schneider Optics Hauppauge, NY -- Test & Measurement World, 10/15/2001

  20. Perspectives – metrology upgradeson-the-table I Chromatic aberration based method • Non-contact method • Precision vs. measuring range vs. allowed surface slope • Typical values: www.stilsa.com

  21. Perspectives – simulation upgrades • Include temperature gradients • Measure actual temperature inside the oven • Apply the temperatures to the simulation • Include cool down process as a standard point • Treat more precisely the glass/form interface

  22. Conclusions • First in-situ shaping measurements (full profile) • Discrepancy between simulations and experiment • Experiment is non-linear x Simulation predict linear bending curve • Higher temperatures are preserved precisely (experiment) • Inoptimal metrology (experiment) • Boundary conditions not well defined (experiment + simulation) • Experience gathered is used for developing new metrology methods for future experiments (including Silicon shaping)

  23. Finito

More Related