| 摘要 |
PURPOSE:To obtain a hollow body with no foreign matter by a method wherein laser beams are irradiated to transmit a preformed body or intermediate formed body. CONSTITUTION:A corrugation type blow molding machine 4 moves like caterpillars so as to successively clamp mold by positioning a tubular thermoplastic preformed body 41 between split molds 42a and 42b, both of which repeat their opening and closing. The tubular preformed body 41 is formed into a hollow formed body by jetting pressure fluid in its interior, and cooled down. After that, the pressure fluid in the interior of the resultant intermediate formed body (c) is discharged and said split molds 42a and 42b are open in order to obtain the intermediate formed bodies (c) connected with one another by flashes (d) or surplus portions. During the course of the intermediate formed body (c) in front of a laser detector 6, laser beams repeatedly traverse the surface of the intermediate formed body (c) in the direction normal to the direction of movement of the body (c) by the action of vibrating mirrors. In order to detect foreign mattes or the like, two laser beams are irradiated to the intermediate formed body (c) from the directions intersecting at right angles by means of two laser beam projectors 61 and 61, two vibrating mirrors 62 and 62 and two laser beam receives 63 and 63. |
