Shape error analysis in ultra-precision grinding of optical glass by using motor-current-based grinding force monitoring

Naoki Iinuma, Boshi Chen, Tappei Kawasato, Yasuhiro Kakinuma

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

4K and 8K technologies are attracting attention in optical industries. The most important mechanical element to enhance the imaging performance is the aspherical lens requiring higher surface quality and higher form accuracy. Currently, the production process of optical lenses consists of brittle-mode grinding and pro-longed polishing process, which play a role of shaping the form and producing the fine surface, respectively. However, this process is not considered to be suitable for manufacturing such higher-quality lenses for 4K and 8K imaging devices because a required form accuracy could not be ensured, and the polishing time gets longer. To enhance the form accuracy and production efficiency, application of ductile-mode grinding is expected to reduce polishing amount. However, the shape error generated by the ductile mode grinding is not clear. Therefore, the purpose of this research is to analyze the relation between the shape error and the grinding force estimated from motor-current in the grinding machine. The motor-current acquisition system in all translational axes and the work spindle is constructed and implemented into a 4-Axis ultraprecision aspherical machine. The grinding force in each axis is derived by subtracting the motor current during non-grinding previously obtained in air-grinding test from the current during grinding. Firstly, the behavior of the motor current in each axis is investigated from the viewpoint of repeatability and position dependency. While the periodic fluctuation of the motor current affected by the influence of permanent magnet in the linear motor is confirmed, it shows high repeatability at each position. This result indicated that grinding force is easily calculated from the motor current with less uncertainty. Then, influence of grinding condition in the range of ductile mode grinding on the shape error is analyzed by monitoring the motor current. Toward the outside of the workpiece, the shape error gradually increases with the increase of motor current, which means larger grinding force at the outer side causes the deformation of the resin grinding wheel.

Original languageEnglish
Title of host publicationManufacturing Processes; Manufacturing Systems
PublisherAmerican Society of Mechanical Engineers
ISBN (Electronic)9780791885819
DOIs
Publication statusPublished - 2022
EventASME 2022 17th International Manufacturing Science and Engineering Conference, MSEC 2022 - West Lafayette, United States
Duration: 2022 Jun 272022 Jul 1

Publication series

NameProceedings of ASME 2022 17th International Manufacturing Science and Engineering Conference, MSEC 2022
Volume2

Conference

ConferenceASME 2022 17th International Manufacturing Science and Engineering Conference, MSEC 2022
Country/TerritoryUnited States
CityWest Lafayette
Period22/6/2722/7/1

Keywords

  • Grinding
  • Shape Error
  • Ultra-precision

ASJC Scopus subject areas

  • Industrial and Manufacturing Engineering

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