Process for improving the surface finish of glass foils
AssigneeSchott Glaswerke
InventorHans-Wilhelm Schulze
Life of this patent
Estimating the term…
Abstract
In a process for improving the smoothness of the surfaces of foils made from thermoplastics materials, particularly glass, the foil is stretched in two directions or dimensions. In a particular method, the foil is laid on top of a first frame and subsequently heated to a temperature which lies in a temperature range within which the foil starts to soften. A second frame which is at the same temperature as that of the foil is then placed on top of the foil so that the latter is effectively clamped between the frames. The two frames and foil is then cooled. The material chosen for the frames is one having a coefficient of thermal expansion smaller than or equal to that of the material of the foil.
Claims19
A process for improving the surface of a glass foil comprising;
- placing the foil on a first frame such that the foil is permitted to expand;
- heating the foil together with the frame at a temperature which lies in the temperature range at which the foil begins to soften without sagging;
- placing a second frame, which is exactly as large and exactly at the same temperature as the first frame, on the foil to clamp the foil within the first and second frame;
- then clamping the foil in both frames such that the foil will contract differentially with respect to the frames upon cooling, and then cooling.
A process for improving the surface of a glass foil comprising:
- placing the foil on a first frame such that the foil can expand;
- heating the foil together with the frame at a temperature which lies in the temperature range at which the foil begins to soften without significant sagging;
- placing a second frame, which is exactly as large and exactly at the same temperature as the first frame, on the foil to clamp the foil within the first and second frame;
- then clamping the foil in both frames such that the foil will contract differentially with respect to the frames upon cooling, and then cooling.
A process for improving the surface finish of glass foil including two dimensional stretching of foil including the steps of placing the foil to be treated by engagement of the marginal regions thereof with a first frame such that the foil can expand, heating the foil and frame to a temperature which lies within a temperature range within which the foil commences to soften without significant sagging;
- placing a second frame, which has been heated to the same temperature as the first frame and foil on the foil, such that the marginal regions of the foil are effectively clamped between the two frames, and then cooling the frames and the foil whereby both frames are composed of a material whose coefficient of thermal expansion is less than the coefficient of the thermal expansion of the foil.
Dependencies are inferred from the claim text.