| 摘要 |
<p>This invention relates to a method of controlling curvature of regions in a shaped thermoplastic sheet. More particularly, it relates to producing bent glass sheets on a mass production basis by passing a series of glass sheets through a heated furnace and then bending each successive sheet to shape by press bending. Temperature measurements are made on a selected portion or portions of selected heat-softened sheets to provide a profile of reference temperatures. After the sheet is shaped and allowed to cool, the radius of curvature errors of selected regions in each of said portions are determined. The magnitude of these errors and the deviation of said reference temperatures from target temperatures determined for said portions determines the nature of one or more changes that are made in one or more parameters of the mass production operation. In a preferred specific embodiment, a composite temperature is determined for each portion from formulae based on reference temperatures of the selected portions. A selected composite temperature, one that provides a desired radius of curvature error in the regions of each selected portion, is determined for each of the portions of the sheet. A target temperature for each of the portions is determined from the selected composite temperature of the respective portions to give a desired radius of curvature error in the regions. According to a specific preferred embodiment of this invention, the parameter of the operation that is changed is the heat pattern in the furnace, which is altered in response to the data derived from reference temperature readings and radius of curvature errors, determined with calculated target temperatures and desired values of radius of curvature errors, respectively, to cause subsequent heat-softened sheets to be heated in such a manner that the temperatures at the different portions approximate the target temperatures calculated from the selected composite temperatures.</p> |
