| 摘要 |
PURPOSE:To surely exhaust air in a metal mold and to always obtain an injected product having no blow hole by arranging a passage such as annular groove, etc., on an outer circular face of a valve rod, a penetrated hole formed pass-through or non-pass through with said passage in a valve guide and pressure detecting apparatus in a piping line connecting said penetrated hole with a hydraulic pressure source. CONSTITUTION:Pressed air is sent from an air source 37 to the penetrated hole 19b of the valve guide 19 by the piping line 36, and then the valve rod 21 is descended and the annular groove 21a for passage arranged in the valve rod 21 is descended during exhausting air through an inner hole 17d and an exhausting hole 17f of a spool 17, under condition of valve open, which a valve body 22 is apart from a valve seat 17e. The penetrated hole 19b is closed by the valve rod 21, and then air pressure increases in the piping line 36 and the left side of the penetrated hole 19b. Next, when the valve is under closing condition which the valve rod 21 is ascended by a molten metal pressure, the above-mentioned air is released from the right side of the penetrated hole 19b under connecting condition between the penetrated hole 19b and the annular groove 21a, and air pressure in the piping line 36 is reduced. As a pressure switch 38 is opened or closed by such an increasing or reducing of air pressure, opening or closing of the valve body 22 is confirmed by arranging a buzzer, etc., in a circuit of the switch 38. |
