Method for controlling compaction
AssigneeCorning Incorporated
InventorsSteven Roy Burdette, Shriram Palanthandalam Madapusi, Jeremy Nathan Payne
Life of this patent
Estimating the term…
Abstract
A method of controlling compaction including obtaining a plurality of sets of process conditions for a plurality of glass ribbons, measuring a compaction value for a glass sheet cut from each glass ribbon of the plurality of glass ribbons, correlating the compaction to the process conditions. The method further includes selecting a predetermined cooling curve including a plurality of cooling rates, modifying the cooling curve by varying cooling rates of the plurality of cooling rates, calculating a predicted compaction value for a glass sheet cut from a glass ribbon drawn using the modified cooling curve, and repeating the modification and predicting until compaction is minimized.
Claims4
A method of controlling compaction, comprising:
- a) measuring compaction values for a plurality of glass sheets cut from a plurality of glass ribbons, the glass ribbons formed with different cooling rates at temperature increments of at least 10° C. in a temperature range equal to or greater than 450° C. and equal to or less than 900° C.;
- b) correlating the measured compaction values with the cooling rates of step a) to obtain a plurality of regression coefficients corresponding to a plurality of temperatures, wherein step b) comprises a linear regression, wherein the linear regression comprises a system of linear equations of the form
- [
- k
- ⋮
- k
- ]
- +
- [
- q
- 1
- 1
- …
- q
- 1
- n
- ⋮
- ⋱
- ⋮
- q
- i
- 1
- …
- q
- i
- n
- ]
- ×
- [
- b
- 1
- ⋮
- b
- n
- ]
- =
- [
- C
- 1
- ⋮
- C
- i
- ]
- ,
- where q represents cooling rate in ° C./second, b represents regression coefficients, C represents compaction in parts per million, i represents a total number of data sets, n represents a total number of the regression coefficients, and k represents an intercept of the regression;
- c) selecting a predetermined cooling curve, the predetermined cooling curve comprising a plurality of predetermined cooling rates at the corresponding plurality of temperatures of step b);
- d) using the plurality of regression coefficients and the plurality of predetermined cooling rates to calculate a predicted compaction value, wherein the predicted compaction value is equal to
- Compaction
- =
- k
- +
- ∑
- n
- =
- 1
- n
- =
- m
- (
- b
- n
- ×
- q
- n
- )
- ,
- where m represents a number of the temperature increments over a temperature range from 450° C. to 900° C.;
- e) modifying the predetermined cooling rates to minimize the predicted compaction value and obtain target cooling rates;
- f) drawing a subsequent glass ribbon using the target cooling rates.
A method of controlling compaction, comprising:
- a) drawing a glass ribbon from a forming body at a first draw rate;
- b) measuring temperature along a centerline of the glass ribbon at a plurality of distances from a bottom edge of the forming body;
- c) calculating cooling rates for the glass ribbon at the plurality of distances based on the measured temperatures;
- d) measuring a compaction value of a glass sheet cut from the glass ribbon;
- e) repeating steps a) through d) for a plurality of glass ribbons drawn at a plurality of draw rates to obtain a plurality of measured compaction values;
- f) correlating the plurality of measured compaction values with the cooling rates at the plurality of distances for the plurality of glass ribbons to obtain a plurality of regression coefficients corresponding to a plurality of temperatures, wherein step f) comprises a linear regression, wherein the linear regression comprises a system of linear equations of the form
- [
- k
- ⋮
- k
- ]
- +
- [
- q
- 1
- 1
- …
- q
- 1
- n
- ⋮
- ⋱
- ⋮
- q
- i
- 1
- …
- q
- i
- n
- ]
- ×
- [
- b
- 1
- ⋮
- b
- n
- ]
- =
- [
- C
- 1
- ⋮
- C
- i
- ]
- ,
- where q represents cooling rate in ° C./second, b represents regression coefficients, C represents compaction in parts per million, i represents a total number of data sets, n represents a total number of the regression coefficients, and k represents an intercept of the regression;
- g) selecting a predetermined cooling curve, the predetermined cooling curve comprising a predetermined cooling rate at each corresponding temperature of the plurality of temperatures;
- h) using the plurality of regression coefficients and the plurality of predetermined cooling rates to obtain a predicted compaction value at a predetermined draw rate, wherein the predicted compaction value is equal to
- Compaction
- =
- k
- +
- ∑
- n
- =
- 1
- n
- =
- m
- (
- b
- n
- ×
- q
- n
- )
- ,
- where m represents a number of the temperature increments over a temperature range from 450° C. to 900° C.;
- i) modifying the predetermined cooling rates to minimize the predicted compaction value at the predetermined draw rate and obtain target cooling rates;
- j) drawing a subsequent glass ribbon using the target cooling rates.
Dependencies are inferred from the claim text.