JP3404051B2 - Film stretching method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for stretching a sealing film on a container or the like, and more particularly to a method for injection-filling a container or the like with a molten resin in a molding die. The present invention relates to a method in which a film is mounted in advance in a molding die when the molding is performed and the stretching is performed. 2. Description of the Related Art A film (so-called virgin film) for sealing a container is provided on a resin container or a frame constituting an edge portion of the container. For example, in a compact cosmetic container, a synthetic resin film serving as the virgin seal is provided on a peripheral edge of an inner plate container containing cosmetics. A conventional method of providing such a virgin film is to mount a virgin film in a molding die for molding a container or the like in advance, and then inject a molten resin into the molding die for molding the container or the like. By doing so, the film was stretched at the same time as forming the container and the like. [0004] However, in the above-mentioned conventional method, the stretched film sometimes becomes loose. If the slack is remarkable and occurs in one direction, there is a possibility that a state like a wavy wrinkle may occur. The present invention has been made to solve the above problems, and has as its technical object to provide a film stretching method capable of stretching a sealing film in a stretched state (stretched state). And [0006] The present invention has the following configuration in order to solve the above technical problems. That is, by mounting a sealing film in advance in the mold of the container or the frame, and by injection-filling a molten resin, in the film stretching method of stretching the film to the peripheral edge of the container or the frame, A groove is provided in one of the upper mold and the lower mold constituting the molding die, a projection is formed on the other, the film is bitten between the projection and the groove, the mounting is performed, and the peripheral edge is formed. A film tensioning method wherein a convex curved surface is provided on a surface in contact with the film, and the film is pressed toward the convex curved surface on a surface of a molded container or frame at the time of injection filling of a molten resin, and a tensile force is applied to the film. It is a setting method. When a film is previously set in a molding die and an upper die and a lower die constituting the molding die are set, the film is bitten by the projections and the grooves. During this biting, the film may be pulled and taut. Furthermore, since the surface in contact with the film at the peripheral edge of the container or the frame is a convex curved surface,
When the molten resin is injected and filled, the film tends to be pulled and further taut on the convex surface. An embodiment of the present invention will be described with reference to FIGS. FIG. 2 is a longitudinal sectional view of a frame 3 provided in a part of the inner container 1 provided inside the compact cosmetic container. On the upper surface of the frame 3, a sealing film 5 called a so-called virgin film is provided. FIG. 3 is an enlarged view of a main part of FIG.
Is inclined toward the inner edge, and the inclined surface is formed as a convex curved surface 7 and continues to a position corresponding to the back side surface of the frame 3. The film 5 is stuck along the convex curved surface 7. FIG. 4 is a longitudinal sectional view of a molding die 9 for molding the frame 3 of FIG. The upper die 11 constituting the forming die 9 includes a cylindrical central upper die 13 and a ring-shaped peripheral upper die 15. The lower mold 17 includes a cylindrical central lower mold 19 and a ring-shaped peripheral lower mold 21. FIG. 1 is an enlarged view of a main part of FIG. A cavity (an empty surface into which the molten resin is injected and filled) 23 machined in accordance with the shape of the frame 3 in which the molding is performed is where three members, namely, a central upper mold 13, a central lower mold 19, and a peripheral upper mold 15 gather. Formed in the part. In the figure, the shape of the cavity 23 corresponds to the shape in which the frame 3 is turned upside down.
The gap 11 between the upper central mold 13 and the lower central mold 19 for inserting the film 5 is 0.08 mm. The peripheral edge of the frame 3 and the surface corresponding to the surface in contact with the film 5 (the upper surface of the frame 3 in FIG. 3) is the upper surface of the lower central mold 19, and the convex curved surface 7 Is formed as a concave curved surface 25. Further, an injection hole 27 for injecting and filling a molten resin into the cavity 23 is provided in the upper central mold 13. A portion near the cavity 13 where the upper peripheral mold 13 and the lower peripheral mold 19 contact each other, that is, the film 5
A ring-shaped groove 29 is formed in the upper peripheral die 13 in a portion where the peripheral portion is sandwiched. Peripheral lower mold 19
Is formed with a ring-shaped protrusion 31. This projection 3
Reference numeral 1 denotes a position at which the groove 1 fits into the groove 29. Groove 29 and protrusion 3
1, there is a gap, the inner gap l2 is 0.15 mm
The dimension 13 of the tip of the projection 31 is 0.7 mm, and the outer gap 14 is 0.15 mm. The gap 15 at the tip of the projection 31 is 0.3 mm,
The height 16 of the projection 31 is 0.5 mm. In this embodiment, the procedure for providing the film 5 on the frame 3 is as follows. That is, first, the film 5 is placed on the central lower mold 19. At this time, the periphery of the film 5 is slightly outside the lower central mold 19. In this state, the peripheral lower mold 21 is set so as to cover the central lower mold 19 from above. Thereby, a part of the peripheral end of the film 5 is sandwiched between the central lower mold 19 and the peripheral lower mold 21. In this state, the upper peripheral die 15 is set. At this time, the groove 29 and the projection 31 are fitted, and the film 5 is bitten therebetween. By this biting, the film 5 is pulled outward (arrow in FIG. 1). Next, the center upper die 13 is set. The cavity 23 is formed by this setting. Then, the molten resin is injected and filled into the formed cavity 23 through the injection hole 27. The setting of the upper central mold 13 and the injection filling may be performed simultaneously. At this time, the lower center mold 19 pushes the film 5 upward in the figure, and the surface of the formed frame 3 pushes the film 5 downward in the figure. Since these pushing forces act on the convex curved surface 7 of the frame 3 (that is, the concave curved surface 25 of the central lower mold 19), the film 5 is given a tensile force (arrow in the figure) as if to shift the film 5 outward. After the frame 3 is thus formed, the peripheral end of the film 5 is cut off by a cutter.
Most of the time, when adopting a method in which the upper mold and the lower mold are joined together to perform molding at the same time as injection filling, for example, a cutter may be provided in the upper mold and the lower mold, and cutting may be performed continuously in the molding operation. Good. As described above, according to the present embodiment, the groove 29
The end of the film 5 is bitten between the protrusions 31 and the convex curved surface 7 of the frame 3 to be formed.
By pulling, the film 5 in a stretched state is stretched on the frame 3 after molding, and the conventional loosening (two-dot chain line in FIG. 2) does not occur. In the above embodiment, the grooves 29 and the projections 31 are provided in a ring shape. However, in other embodiments, the grooves 29 and the protrusions 31 may be provided only in a part instead of the ring shape. For example, they may be provided partially discontinuously. The frame 3 is, as shown in FIGS.
A tongue piece 33 for peeling off the film 5 may be provided. That is, a tongue piece 33 is provided outside the frame body 3, and the thickness between the tongue piece 33 and the frame body 3 is thin (see FIG. 7). If the piece 33 is lifted upward, the tongue piece 33 is broken, and the film 5 is peeled off by further lifting the tongue piece 33, so that the cosmetic of the inner dish container 1 can be used. In such an embodiment, the groove 29 and the projection 3 provided in the mold 9 are provided.
1 can be provided only in a portion of the periphery of the frame 3 where the tongue piece 33 is not formed. As described above, according to the film stretching method of the present invention, when the container or the frame is formed, the film is caught by the groove and the projection, and the projection is formed. By being pulled by the curved surface, it can be in a stretched tensioned state.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an enlarged view of a main part I of a cross section of a molding die used for a film stretching method according to one embodiment of the present invention. FIG. 2 is an overall vertical sectional view of a frame formed by the mold of FIG. 1; FIG. 3 is an enlarged view of a main part III of FIG. 2; FIG. 4 is a longitudinal sectional view showing the entire molding die of FIG. 1; FIG. 5 is a plan view of a frame according to another embodiment. FIG. 6 is a longitudinal sectional view of FIG. FIG. 7 is an enlarged view of a main part VII of FIG. 6; [Description of Signs] 1 ... Inner dish container 3 ... Frame body 5 ... Film (virgin film) 7 ... Convex curved surface 9 ... Molding mold 13 ... Central upper mold 15 ... Peripheral upper mold 19 ... Central lower mold 21 ... Peripheral lower mold 23 ... cavity 29 ... groove 31 ... projection

──────────────────────────────────────────────────の Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B65B 7/28 B29C 45/14

Claims (1)

(57) [Claim 1] A sealing film is mounted in a mold of a container or a frame in advance, and molten resin is injected and filled, so that the peripheral edge of the container or the frame is In a film stretching method for stretching a film, a groove is provided on one of an upper mold and a lower mold constituting the molding die, and a projection is formed on the other, and the film is engaged between the projection and the groove. In addition, the mounting is performed, and a convex curved surface is provided on a surface in contact with the film of the peripheral edge, and the film is pressed toward the convex curved surface on the surface of the container or the frame formed at the time of injection filling of the molten resin. A film stretching method characterized by applying a tensile force to a film.