FIELD OF INVENTION
The present invention relates generally to the molding of plastic parts, and specifically relates to a device for blow-molding a thermoplastic into the shape of an indented female connector.
BACKGROUND OF THE INVENTION
Blow molding of plastics to form hollow shapes such as bottles, containers or the like is well known. Some shapes are difficult to mold into a hollow container with a blow molding process. An example of a shape that is difficult to mold is an indented female connector having a set of internal ribs for engaging with a male connector. Accordingly, there is a need for an improved device for molding an indented female connector as part of a hollow object.
SUMMARY OF THE INVENTION
The present invention meets the above-described need by providing a male mold component that can be inserted into the mold to form the indented female connector in the container and that can be removed without damaging the ribs formed in the indented connector.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is illustrated in the drawings in which like reference characters designate the same or similar parts throughout the figures of which:
FIG. 1 is a sectional side elevational view of the male mold component positioned inside a portion of the object to be molded;
FIG. 2 is a sectional side elevational view of the indented female connector; and,
FIG. 3 is a sectional side elevational view showing the mold component in broken lines as it is being removed from the indented female connector.
DETAILED DESCRIPTION
Referring generally to FIGS. 1-3 and initially to FIG. 1, a portion of a hollow molded object 10 is shown in a sectional side view. The portion shown is an indented female connector 16 that is formed in the side of the hollow object 10. The hollow object 10 is formed from thermoplastic materials by blow molding techniques known to those of ordinary skill in the art. A male mold component 13 is inserted into the mold to form the indented female connector 16 shown. Once the female connector 16 has been molded, the male mold component 13 is removed from the mold as described hereinafter.
Referring to FIG. 2, the indented female connector 16 is surrounded by a surface 19. The surface 19 is formed on an upper wall 20 having a thickness indicated at 21. The surface 19 is disposed substantially perpendicular to a set of inside walls 25 extending inward toward a rib 28 that is integrally formed in the inside walls during the molding process. Depending on the shape of the opening, the rib 28 may be formed on some or all of the inside walls 25. For a circular opening, the rib 28 may be formed in an annular configuration. For a rectangular opening the rib 28 may extend only along the opposed major lengths of the rectangle.
The rib 28 may extend from the inner wall inward at an angle of approximately forty-five degrees. As shown in FIG. 2, there is a pair of ribs 28 facing each other and extending inward at approximately a forty-five degree angle from an axis 31 parallel to the inside wall 25. With reference to the orientation of FIG. 2, the side walls 25 may continue downward and join by means of a section 34 disposed at the bottom of the connector 16. Although the section 34 is curved in the drawings, the section 34 may be formed in other shapes as well.
Between the top of surface 19 and the rib 28 is a flex section having a dimension 37. The distance along the rib is a locking surface 40, and the portion below the rib 28 is a receiving surface 43. The opening between opposed ribs 28 has a dimension 44 that will be discussed below.
Turning to FIG. 3, after the blow molding process is completed, the male mold component 13 is removed from the indented female connector 16 by pulling it in a direction substantially perpendicular to top surface 19. The opening for removing the male mold component 13 is narrowest at the point between the ribs 28. This distance is also indicated in FIG. 2 as dimension 44. When the male mold component 13 is removed, the ribs 28 have to bend away from each other in order to accommodate the large diameter 60 of the lower portion 63 of the male mold component 13.
Returning to FIG. 2, it has been discovered that in order to form the ribs 28 and to successfully remove the male mold component 13 without damaging the ribs 28, a certain relationship between thickness 21 and the dimension 37 applies. If dimension 37 is greater than thickness 21, the mold 13 can be removed without damaging ribs 28. If dimension 37 is less than or equal to thickness 21, the ribs 28 are typically destroyed when the mold 13 is removed.
While the invention has been described in connection with certain embodiments, it is not intended to limit the scope of the invention to the particular forms set forth, but, on the contrary, it is intended to cover such alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.
Patent Application
20050070167
