| 摘要 |
PROBLEM TO BE SOLVED: To prevent a slit cut length and a cut width from changing and a flap from shifting by making an orifice forming wall of a slit valve thick and also by forming both an outer surface and an inner surface of the forming wall of a spherical face. SOLUTION: The valve head 51 includes an orifice forming wall 58, a holding cylinder wall 59 connected to the orifice forming wall 58 and a thin coupling wall 60 connected downward from the holding cylinder wall 59 to an upper end of a cylinder wall 53. An outer surface 61 of the orifice forming wall 58 is formed in a spherical face having a predetermined radius, while its inner surface 62 is formed in a spherical face having a radius larger than that of the outer surface 61, so that a center part is thinner than a peripheral part. Since the orifice forming wall 58 is formed to be thick, even if discharging is repeated and tearing force repetitively functions, a cut length and a width of a slit 64 can be prevented from increasing, and also flaps 65a, b, c can be prevented from shifting from one another. |
