| 摘要 |
PURPOSE:To ensure heat sealing even when a foreign substance is present between films to be heat sealed by providing a protuberant part having a nearly arc-shaped cross section at a prescribed position on the surface of a sealing rubber and forming a projection on the top of the protuberant part so that the projection will force aside the foreign substance. CONSTITUTION:An underside film 14 having recesses 14a into which objects to be packaged are put and being curved with an upper-side film 18 is fed into a vacuum chamber 19. When a foreign substance 30 is present between the upper and lower films (14, 18), an underside vacuum box is raised so that a small projection 29 of a sealing rubber 26 comes in contact with the underside film 14. When the space between a hot plate 25 and the sealing rubber 26 is reduced due to descending of the hot plate 25, the foreign substance 30 is forced aside by the small projection 29. When the space is further narrowed, the small projection 29 will recede into a protuberant part 27, so that the surface of the sealing rubber 26 forms a smooth curve, and a clamping force produced between the projection 29 and the hot plate 25 will give relatively firm heat sealing of the upper and lower films (14, 18). When the space is still further narrowed, firmer heat sealing can be realized due to the restoring force of the protuberant part 27. |
