| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and apparatus for press forming, by which a funnel glass for a large size cathode-ray tube can be press formed with high productivity. SOLUTION: The apparatus for press forming is composed of a ram cylinder 5, a large amount discharge pump line 30 having a large amount discharge pump 33 and an accumulator 31, and a high pressure pump line 40 having a high pressure pump 42. In the method for press forming, when a gob is pressed, a plunger 4 is allowed to descend until it reaches a predetermined position by supplying an operating oil from the large amount discharge pump line 30 and the high pressure pump line 40 to the ram cylinder 5. When the plunger 4 reaches the predetermined position, the plunger 4 is further allowed to descend by switching a hydraulic servo valve 41 and supplying the operating oil having a prescribed pressure from only the high pressure pump line 40. After a predetermined time, the plunger 4 is allowed to ascend by switching the hydraulic servo valve 41 and supplying the operating oil from the high pressure pump line 40 and the large amount discharge pump line 30 to the ram cylinder 5. COPYRIGHT: (C)2004,JPO&NCIPI
|
