| 摘要 |
PURPOSE:To prevent the crack of a glass face by providing the residual distortion of the glass face in the direction perpendicular to the tube axis with a tension distortion at the central part of the glass face and a compression distrotion in the peripheral section. CONSTITUTION:Since the distortion which is neutral in the direction perpendicular to the tube axis generates a tension distortion toward the face peripheral section of a cathode-ray tube by the thermal expansion of the central part, the face generates a crack by the temperature difference between the central part and peripheral section. This event occurs since the central part is heated. If any residual compression distortion is previously reserved in the peripheral section, there is no possibility of growth of the crack during operation since the compression distortion is canceled and offset or reduced against the tension distrotion. To reserve such a residual compression distortion, a material with the large heating capacity of an asbestos plate 5 or the like is first heated beyond the slow cooling point and is then quenched below the slow cooling point 6 while it is being made to touch both surfaces of the central part 2. Since the peripheral 3 is quenched because the central part 2 is lacking of the asbestos plate 5, the residual compression distortion is reserved in the peripheral section 3. |
