JP2005324484A - Thick peripheral-walled cap with reduced weight and injection molding mold - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thick peripheral-walled cap with reduced weight which features the realization of weight reduction without changing its appearance and shows successful presentability and stable dimensional precision, and an injection molding die. <P>SOLUTION: This thick peripheral-walled cap has a wall thickness of not less than 2.5 mm in its peripheral wall 120. In addition, a plurality of weight-reducing cavity channels 130 with a height equal to not less than 90% of the height from the lower end surface of the peripheral wall to the lower surface of a top, are arranged at an equal interval in the peripheral direction from the lower end surface of the peripheral wall to the upper part, in almost the center position, in the thickness direction, of the peripheral wall. Thus the weight of the cap can be reduced by 7 to 11%. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a weight-reduced peripheral wall thick cap and an injection mold that reduce the weight of a peripheral wall thick cap having a peripheral wall thickness of 2.5 mm or more.

  Conventionally, a plastic cap in which a thermoplastic resin such as polypropylene or polyethylene is injection-molded in the neck of a container such as a plastic bottle, a glass bottle or a wide-mouth container filled with contents to seal or seal the container. However, it was mounted by screwing or occlusion. Recently, from the standpoints of environmental protection and resource saving, the amount of plastic in the plastic container material has been reduced, and in particular, reduction in the weight of the thick wall cap has been strongly demanded.

  However, as a method of reducing the weight of the peripheral wall thick cap without changing the wall thickness of the peripheral wall, the weight of the cap is usually changed by changing the shape and depth of the vertical knurled eye provided on the outer peripheral surface of the peripheral wall of the cap. However, it has been difficult to reduce the weight in accordance with expectations because this method naturally limits the amount of weight reduction.

  The present invention solves the problems associated with reducing the weight of the above-mentioned conventional peripheral wall thick wall cap, and can reduce the weight without changing the appearance, and also has good appearance and stable dimensional accuracy. A weight-reduced peripheral wall thick wall cap and an injection mold are provided.

  That is, according to the first aspect of the present invention, in a peripheral wall thickness cap having a peripheral wall thickness of 2.5 mm or more, the height from the lower end surface of the peripheral wall to the bottom surface of the top plate is approximately at the center position in the thickness direction of the peripheral wall. The weight reduction is characterized by reducing the weight of the cap by 7 to 11% by providing a plurality of hollow groove portions with a height of 90% or more at equal intervals in the circumferential direction upward from the lower end surface of the peripheral wall. This is a thick wall cap.

  According to a second aspect of the present invention, in the injection mold for molding a thick wall cap as a molded product, a substantially central position in the left-right direction of the peripheral wall molding cavity formed by the female mold and the male mold is provided. An injection mold characterized in that a plurality of fin-like pins for forming weight-reducing hollow grooves on the peripheral wall of a molded product are provided on the upper surface of the male mold at equal intervals in the circumferential direction.

  Since the weight-reduced peripheral wall thick cap of the present invention is provided with a plurality of weight-reducing cavity grooves at equal intervals in the circumferential direction at approximately the center position in the thickness direction of the peripheral wall from the lower end surface of the peripheral wall. The plastic weight corresponding to the volume of the plurality of weight-reducing hollow grooves can be reduced by 7 to 11% from the original cap weight without changing the appearance.

  The weight-reduced peripheral wall thick cap of the present invention is provided with a weight-reduced cavity groove portion that extends upward from the lower end surface of the peripheral wall at equal intervals in the circumferential direction in the peripheral wall, and the cavity action of this weight-reduced cavity groove portion Due to the effect, even if the wall thickness of the peripheral wall is 2.5 mm or more, sink marks that are likely to occur with the wall thickness are reduced, so that the appearance of the cap is improved and the dimensional accuracy of the cap is stabilized. .

  Next, an embodiment of the weight-reduced peripheral wall thick cap of the present invention will be described in detail with reference to the drawings.

  Fig.1 (a) is sectional drawing of the weight reduction surrounding wall thick cap of this embodiment, FIG.1 (b) is a bottom view. FIG. 2 is an explanatory view showing a main part of the structure of an injection mold for molding the weight-reduced peripheral wall thick wall cap of this embodiment.

  The weight-reduced peripheral wall thick cap of this embodiment is a peripheral wall thick wall having a peripheral wall thickness of 2.5 mm or more that is attached to the mouth and neck of a container such as a plastic bottle, a glass bottle, or a wide-mouth container by screwing or occlusion. It is a cap. And it is produced by an injection molding method using a thermoplastic resin such as polypropylene or polyethylene.

  As shown in FIGS. 1 (a) and 1 (b), the structure of the weight-reduced peripheral wall thick wall cap (100) of this embodiment is composed of a top plate (110) and a peripheral wall (120). The packing (300) is attached by providing a packing engaging ring (123) on the inner peripheral surface of the upper end portion of the peripheral wall. A female screw (121) is provided on the inner peripheral surface of the peripheral wall to be screwed with the male screw of the mouth and neck of the container, and the height from the lower end surface of the peripheral wall to the lower surface of the top plate is approximately 90 at the center in the thickness direction of the peripheral wall. A plurality of, for example, 10 weight reducing hollow grooves (130) having a height of at least% are provided at equal intervals in the circumferential direction upward from the lower surface of the peripheral wall. Then, by providing the weight-reducing hollow groove portion on the peripheral wall, the weight of the cap is reduced by 7 to 11% compared to the case where the weight-reducing hollow groove portion is not provided. If the weight is reduced by 7% or less, the reduction effect is small, and if it is 11% or more, the physical properties of the cap may be caused by the reduction. Further, when the height of the weight-reducing hollow groove is 90% or less of the height from the lower end surface of the peripheral wall to the lower surface of the top plate, the reduction effect may be insufficient, and the thickness of the upper end portion of the peripheral wall may be insufficient. Since the thickness becomes thicker, the upper end portion of the peripheral wall may become sinked and the appearance may be impaired.

  As shown in FIG. 2, the injection mold (200) for molding the weight-reduced peripheral wall thick wall cap of the present embodiment is composed of a male mold (210) and a female mold (220). When the mold is clamped, the peripheral wall forming cavity (230) and the top plate forming cavity (240) are formed as so-called cavities in which the female mold and the male mold form a molded product. A plurality of, for example, ten fin-like pins (211) for forming a weight-reducing cavity groove portion are provided at equal intervals in the circumferential direction on the upper surface of the male mold at a substantially central position in the left-right direction of the cavity for use.

  In the injection mold for molding the weight-reduced peripheral wall thick cap described above, the fin-shaped pin for forming the weight-reduced cavity groove projecting from the male mold has a female screw on the inner peripheral surface of the peripheral wall. It is also possible to use the provided cap as a rotation pin when turning off at the time of mold release.

  The outer diameter is 39.8 mm, the outer height is 26.0 mm, the inner height is 23.6 mm, and the wall thickness is 2.5 mm. When 10 weight-reduced hollow grooves having a circumferential length of 7.0 mm at 0.7 mm are provided at equal intervals in the circumferential direction, the cap has a smaller length than that in the case where no weight-reduced hollow grooves are provided. The weight could be reduced by 10-11%. Further, the appearance of the cap was good and the dimensional accuracy was stable.

(A) is sectional drawing of the weight reduction surrounding wall thick wall cap of one Embodiment of this invention, (b) is a bottom view. It is explanatory drawing which shows the principal part of the metal mold | die for injection molding of one Embodiment for shape | molding the weight reduction surrounding wall thick wall cap of this invention.

Explanation of symbols

100 ... Weight-reduced peripheral wall thick cap 110 ... Top plate 120 ... Peripheral wall 121 ... Female thread 122 ... Knurling 123 ... Packing engagement ring 130 ... Weight-reducing hollow groove 200 ... Injection molding gold Mold 210 ... Male mold 211 ... Fin-shaped pin 220 ... Female mold 230 ... Peripheral wall molding cavity 240 ... Top plate molding cavity

Claims (2)

  In a peripheral wall thickness cap with a peripheral wall thickness of 2.5 mm or more, a weight-reducing hollow groove portion having a height of 90% or more of the height from the lower end surface of the peripheral wall to the bottom surface of the top plate is located at substantially the center position in the thickness direction of the peripheral wall. A weight-reduced peripheral wall thick cap characterized in that a plurality of the caps are provided at equal intervals in the circumferential direction upward from the lower end surface of the peripheral wall to reduce the weight of the cap by 7 to 11%.   In an injection mold that molds a thick wall cap as a molded product, the weight of the peripheral wall of the molded product is reduced on the upper surface of the male mold at the center in the horizontal direction of the cavity for molding the peripheral wall formed by the female mold and the male mold. An injection mold characterized in that a plurality of fin-like pins for forming a hollow groove are provided at regular intervals in the circumferential direction.

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