Semester

Fall

Date of Graduation

2000

Document Type

Dissertation

Degree Type

PhD

College

Statler College of Engineering and Mineral Resources

Department

Mechanical and Aerospace Engineering

Committee Chair

John E. Sneckenberger.

Abstract

Existing glass crack-off methods often result in considerable loss of glassware and require subsequent edge finishing that is labor intensive. The main objective of this dissertation is to contribute to the development of a laser-enhanced cutting and finishing method that will decrease waste and improve productivity in the manufacturing of handblown glass.;The main objectives of this dissertation were to perform modeling and simulation of the laser glass interaction, to contribute to the lab prototype machine construction, to participate in experiments to investigate the process parameters governing successful glass cutting, and to pursue the design and validation of controls for the laser glass cutting machine.;A 3-D laser heat source model was developed. The LGCSim program based on this 3-D heat source model as well as the classical 3-D heat conduction model was developed to simulate the laser glass interaction. Results from the simulation showed that the peak glass temperature can reach 3500°C, the time constant for glass temperature decay after laser striking is 0.02 second, and the required laser power to cut typical glassware has to be around 1000 W. Simulation-based parametric studies showed that higher laser power is significantly beneficial to the process, higher glassware rotation speed is beneficial to the process too, and larger glassware diameter and thickness have detrimental effects on the process.;It was experimentally shown that the glassware should be preheated to its annealing temperature to avoid cracking. The pulling force is necessary to enable quick and stable cutting. It is better to increase the rotation speed although it is limited mechanically. The laser power has a significant beneficial effect on the melting and a detrimental effect on the groove depth. It is best that the laser beam be kept focused on the cutting ring surface. A gas purge can help to obtain narrower and deeper grooves.;Empirical models were developed to predict the melting depth and the groove depth based on the simulation and experimental results. A system controller was developed. Four subsystem components in the control system were designed and conceptually proven to be operationally acceptable for the lab prototype machine.

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