| 摘要 |
PURPOSE:To allow reduction in the outer diameter of a vent plug by deforming its large diametral portion elastically when the vent plug is fitted in the plug mounting hole of a mold and, after being fitted, the plug is brought into sure and close contact with the inner wall of the plug mounting hole by the spring effect of the plug by a structure wherein a diametral slit is provided at the large diametral portion of the vent plug so as to be extended in the axis line direction. CONSTITUTION:The outer diameter D1 at the large diametral portion 1 is made to be slightly larger than the inner diameter D2 of the plug mounting hole 5 of a mold 4. The outer diameter D3 at the small diametral portion 3 is made so that a gap 6 is produced between the diameter D3 and the inner peripheral wall 5a of the plug mounting hole 5. A diametral slit 7 with the width W1 and the length L3 in the axis line direction is provided at the end face 1a on the inner surface side of the mold of the large diametral portion 1. An outer side open groove 8 with the width W2 is provided over the range from the position distant from the end face 1a on the inner surface side of the mold of the large diametral portion by the distance of L4 to the end face 3b of the small diametral portion 3 at the position in the peripheral direction so as to communicate with the slit 7. A vent plug as mentioned above is easily fitted to and dismounted from the mold. In addition, the finishing work of the plug end after fitting is unnecessary. |
