JP3303438B2 - Mold equipment for injection molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a split-type injection molding die apparatus for molding a long-axis object, and more particularly to a mold apparatus effective for molding in which both ends of the long-axis object to be molded are different. Things.

[0002]

2. Description of the Related Art Conventionally, a mold apparatus as shown in FIG. 10 has been known as a split-type injection mold apparatus for molding a long shaft object 101. FIG. The lower mold 102 is formed with about half of the cavity 103 for molding the long-axis object 101, and the cavity 103 is formed below the cavity 103.
An ejector pin 104 for projecting a molded product (the long-axis object 101) is slidably disposed along 103. However, since the shape of the both ends of the long axis object 101 is different, even if the three ejector pins 104 try to protrude at the same time, the thin side of the long axis object 101 (the left end in the figure).
Shrinks quickly, and the release resistance on the thick side (right end in the figure) is large. As a result, the thick side is released from the cavity 104 with a delay compared to the thin side. For this reason, in the state where the long axis object 101 is bent (curved), the cavity-1
The mold 104 is released from the mold, and the thick side of the long-axis object 101 is engaged with the cavity 104 at that time. Due to this biting action, scratches, cracks, bends, and the like are generated at the right end of the long shaft object 101, and the value as a product is reduced.
Therefore, as shown in FIG. 11, a method has been adopted in which the balance pin 105 is provided so as to protrude into the cavity 104 so as to bite the long-axis object 101 during molding. To explain the operation, the ejector
When the pin (104) tries to protrude the molded product (the long-axis object 101), the balance pin 105 causes the thin side of the long-axis object 101 to become a resistance, and the mold is delayed and released. The delay operation on the thin side is synchronized with the delay operation on the thick side, and both ends are released at the same time, so that scratches and cracks can be prevented.

[0003]

However, even in the prior art described above, the long-axis object 101 is slightly reduced.
Therefore, when the long axis object 101 comes out of the balance pin 105, one of the holes 106 formed by the balance pin is used.
The inner peripheral surface of the part is strongly rubbed by the top of the balance pin. As a result, as shown in FIG. 12, a curl 107 occurred near the short opening of the hole 106, which also deteriorated the appearance.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and is directed to a split-type injection molding apparatus for molding a long shaft, in which a cavity of a mold is provided at a lower portion. In the injection molding apparatus, an ejector pin for projecting the molded product from the cavity is disposed, and a balance pin for performing a resistance action when the molded product is projected is disposed, and the balance pin is protruded into the cavity. The gist of the present invention is that the projecting portion of the balance pin includes a small diameter portion and a large diameter portion.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. One example of a long-axis object to be formed first will be described with reference to FIGS. The long-axis object 1 is used as a center axis of a red holder-type writing instrument that stores a plurality of writing objects described later. The central shaft 1 has a small diameter portion 2 and a large diameter portion 3.
It is composed of In addition, a slit 4 is formed at the center of the center shaft 1 in the longitudinal direction. Further, a hole 7 composed of a small diameter hole 5 and a large diameter hole 6 formed by a balance pin, which will be described later, is formed continuously at an intermediate portion of the center shaft 1.

Next, a mold apparatus for molding the center shaft 1 will be described with reference to FIGS. 4 and 5. In a lower mold 9 of a mold 8 of a split type, a cavity 10 for forming a molded product (center shaft) 1 is formed. Have been. In the cavity 10, three ejector pins 11 for projecting a molded product at appropriate intervals are arranged so as to be able to protrude from the cavity 10.

A balance pin 12 is disposed on the small diameter side of the cavity 10 so as to protrude into the cavity 10. And the balance pin 1
2 has a small diameter portion 13 and a large diameter portion 14 as shown in FIG.
It is configured to be connected continuously. Incidentally, a step 15 may be formed at a continuous portion between the small diameter portion 13 and the large diameter portion 14 as shown in FIG. 6, and a tapered large portion as shown in FIGS. The diameter portion 16 may be used, and various shapes can be selected.

Next, the operation will be described. The mold is opened, and the ejector pin 11 urges the molded product 1 into the cavity-1.
Release from 0. At this time, as described in the related art, the balance pin 12 slides on the inner surface of the small diameter hole 5. At this time, as shown in FIG. 3, the winding 17 occurs, but since it is hidden inside the center shaft 1, there is no problem in appearance.

In the present invention, as described in the above embodiment, when forming a center shaft (long-axis object) inserted in a red holder-type writing tool capable of accommodating a plurality of writing bodies, This is particularly effective (see FIG. 9). Hereinafter, the red holder-type writing implement will be briefly described. First, the center shaft 1 is rotated, and the writing body 18 to be selected is provided with a damper-1.
Position 9 Next, the knock member 20 is pressed to incline the front of the damper 19. The damper-19
The one writing body 18 comes out of the core chamber 21 (falls). As described above, in the center shaft 1 where the sliding action occurs with the surface of the writing body 18 due to the rotation, particularly on the surface of the center shaft 1 (the sliding surface with the writing body), the writing body 18 is not damaged (shaving powder). This may cause poor appearance of the cursive writing), burrs (turn-up), edges and the like generated during molding must be prevented as much as possible.

[0010]

According to the present invention, there is provided a split-type injection molding apparatus for molding a long-axis object, wherein an ejector pin for projecting a molded product from a cavity is provided below a cavity of the mold, and a product is provided. In the injection molding apparatus in which a balance pin that exerts a resistance action at the time of protrusion is arranged and the balance pin is protruded into the cavity, the protrusion of the balance pin is composed of a small diameter portion and a large diameter portion. Accordingly, it is possible to provide a mold apparatus for molding a long-axis object having a good external appearance.

[Brief description of the drawings]

FIG. 1 is a plan view showing a long-axis object formed according to an embodiment of the present invention.

FIG. 2 is a vertical sectional view taken along line AA corresponding to FIG.

FIG. 3 is an enlarged view of a portion B corresponding to FIG. 2;

FIG. 4 is a longitudinal sectional view showing an embodiment of the present invention.

FIG. 5 is an enlarged view of a portion C corresponding to FIG. 4;

FIG. 6 is an enlarged view showing another embodiment of the balance pin corresponding to FIG. 5;

FIG. 7 is an enlarged view showing still another embodiment of the balance pin corresponding to FIG. 5;

FIG. 8 is an enlarged view showing still another embodiment of the balance pin corresponding to FIG. 5;

FIG. 9 is a longitudinal sectional view showing a red holder-type writing instrument.

FIG. 10 is a longitudinal sectional view showing a conventional technique.

FIG. 11 is a longitudinal sectional view showing another conventional technique.

FIG. 12 is a front view showing a molded product formed by a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 101 Long axis object 2 Small diameter part 3 Large diameter part 4 Slit 5 Small diameter hole 6 Large diameter hole 7,106 hole 8 Die 9,102 Lower die 10,103 Cavity 11,104 Ejector pin 12,105 Balance pin 13 Small-diameter portion of balance pin 14 Large-diameter portion of balance pin 15 Step portion 16 Tapered large-diameter portion 17, 107

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B29C 45/40 B43K 3/00 B43K 21/00

Claims (1)

(57) [Claims] 1. A split-type injection-molding mold apparatus for molding a long-axis object, wherein an ejector pin for projecting a molded product from a cavity is disposed below a cavity of the mold, and a resistance action when the product is projected. In an injection molding apparatus in which a balance pin is provided and the balance pin protrudes into the cavity, the protrusion of the balance pin is constituted by a small diameter portion and a large diameter portion. Molding equipment for injection molding.