| 摘要 |
PURPOSE:To prevent a molding surface from formation of voids or non-charged part by providing small-diameter holes for air vent in a upper or lower mold. CONSTITUTION:Several small-diameter holes 7 for air vent are provided in a section of the bottom surface of the lower mold 2 where gas or air is likely to stagnate. The hole diameter is about 1-2mm, but since the fluidity of the material depends on the viscosity of the material, foaming conditions, discharge pressure and other factors, it is desirable to change the hole diameter according to the material used and other elements. Each hole is provided with a sufficient draft to keep it free from being stuffed with the material. In order to facilitate drilling of the holes 7, a thin- walled portion 8 is provided at the section of the bottom surface of the lower mold 2 where the holes 7 are provided. According to this arrangement, gas and air are discharged out even if the material is reacted and solidified at a high speed, so that there is no possibility of producing voids or non-charged area in the molding surface. |
