| 摘要 |
PURPOSE:To enable the uniform and quick temp. rise of a shadow mask and the press forming of high accuracy by providing a freely slidable heating body in the axial direction which connects the upperpart and lower part manihold structure bodies inside a knockout and by heating a flat mask. CONSTITUTION:The blank 3 of a shadow mask is heated by pinching it with the peripheral presser 2 incorporating an electric heater and a die 4. The heat is transferred by its conduction from the center part of the blank 3 to the peripheral part by closely fitting a heating body 6 with its ascending. The heat is transferred for the center by its conduction even from the pinching part of the blank 3, simultaneously, the blank 3 is heated by the radiation from the punch 1 incorporating the electric heater. After the blank 3 being heated to the prescribed temp., the heating body 6 is descended and stored in the boring part of the knockout 5. The main surface part of the shadow mask is thereafter formed in curved surface by descending the punch 1. Then pistons 10, 12 are descended, the punch 1 is further descended, the skirt part of the shadow mask is subjected to drawing by the punch 1 and die 4 and the forming is completed.
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