| 摘要 |
PURPOSE:To obtain a leisure boat made of plastics capable of high speed sailing, by forming an edge of section thickness at the bottom part of the stern. CONSTITUTION:Plastic material is melted in a heating pipe 8 and dropped from a head 9 as cylindrical parison A. Here a slide mold 11 is recessed through an oil pressure cylinder 12. Accordingly the parison A drops into molds 10, 10 in the state where stern bottom G is expanded largely. As an air is pressurized into the parison from blowing inlet, the molten plastic material expands outwardly from rear outer wall 5. Here plastic material has been excessively fed at boundary portion of ship bottom 4 and rear outer side wall 5 of its master. From this state the mold is kept contacted closely and air pressurization is completed, when the edge 6 of section thickness having required angle is formed. At the cross section of the bottom part G of the stern of hull 1 shaped as above, rectangular or sharp-edged edge 6 of section thickness is formed. |
