| 摘要 |
PURPOSE:To obtain a small-sized expansion pressure detecting device wherein measuring error is small, responding speed is fast, no trace is left on a molded piece, and measuring is simple by providing a metal thin film for receiving expansion pressure, a pressure detecting means, sealing liquid, and a signal conversion means in an ejector pin. CONSTITUTION:An ejector pin 1 is constituted of an embedding member 2 with a shape almost cylindrical to be embedded in a hole of a mold and a sliding member 3. In the embedding member 2, a conduit 10 is embedded. One tip 10a of the conduit is made to be thicker than other part. At its opening face, a diaphragn 11 with a thickness of 0.1-1.2mm is welded so as to receive expansion pressure to be generated by secondary expansion of expandable plastic resin particles. To other tip 10b of the conduit 10, a pressure sensor 13 is welded through a joint 14. In the conduit, a sealing liquid 12 such as silicone oil is sealed, so that the expansion pressure is transmitted to the pressure sensor 13 correctly. Biased quantity of a sensing part 13a is converted into a current value, outputted to a molding machine control device, so that a molding condition for expansion molding is set. |
