JPH0516183A - Metal mold for injection molding and method for preparation of metal mold - Google Patents

Abstract

PURPOSE:To perform simply and surely vent on the surface of molding and to solve various problems caused by shortage of vent by providing a vent path communicating from the surface of molding to the surface of division on either a male mold or a female mold in a metal mold wherein gas is vented from the surface of molding being parallel to the opening and closing direction. CONSTITUTION:A metal mold 1 is constituted of a movable mold 2 forming the inner face side of a molded body and a fixed mold 3 forming the outer face side of the molded body and a cavity is formed between them. In this case, a vent path 10 is provided in the two stage projection 2a of the movable mold 2. The vent path 10 forms a perforating hole 11 in the two stage projection 2a and one end thereof is opened on a surface of molding 6a and another end is communicated with a gas storage groove 12. In addition, a left pin 13 preventing molten resin from penetration and making only gas pass through is fitted in one end on the side of the surface 6a of molding of the perforating hole 11. Only gas retained on the surface of molding 6a is vented to the outside of the cavity from the surface of division 7 through the gas storage groove 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection-molding die and a method for producing a die, in which gas accumulated on a molding surface parallel to the opening / closing direction of the die is released.

[0002]

2. Description of the Related Art Conventionally, for example, in an injection mold for molding a resin molded product, if the gas inside the cavity is insufficiently depleted, the strength of the molded product will decrease due to insufficient filling of the molten resin, and the dimensional accuracy will change. Or, since a defective phenomenon such as deterioration of the surface condition occurs, it is necessary to take appropriate degassing means. For this reason, for example,
Gas venting means for molds such as No. 1-71419 and No. 62-67722 are known as general gas venting structures, and all of these have a vent hole provided in the mold. It is extended along the opening and closing direction of to make the inside of the cavity communicate with the external space.

[0003]

However, there has been a problem that a resin molded product such as an instrument panel of an automobile cannot be completely degassed by a conventional degassing means. That is, as shown in FIG. 4, the instrument panel 20 includes a box portion 21 for accommodating meters, and the left side surface portion 22, the right side surface portion 23, and the upper surface portion 24 that form each side of the box portion 21. The protruding portions of the lower surface portion 25 are planes parallel to the mold opening / closing direction during molding of the mold, and in particular, gas is likely to stay on the left side surface portion 22 on the side far from the gate 26 for injecting the resin. There was a problem that a defective portion 28 was generated. The conventional method of degassing cannot deal with such a method of degassing from the molding surface parallel to the opening / closing direction of the mold.

[0004]

In order to solve the above problems, the present invention comprises a mold capable of releasing gas from a molding surface substantially parallel to the opening / closing direction of the mold. That is, a gas vent passage communicating from the molding surface to the split surface of the mold was provided in either the male or female mold. Also, when multiple molding surfaces face each other,
A plurality of gas vent channels are provided so as to communicate with each molding surface and the division surface. Then, a through hole was provided between the molding surface and the dividing surface as a gas release channel, a discarding pin was provided on the molding surface side of the through hole, and a gas reservoir groove was formed in the mold on the dividing surface side. Further, as a discarding pin, a cylindrical member having a diameter substantially the same as that of the through hole was hit with a punch or the like to form a dent, and then inserted into the through hole.

[0005]

The gas staying on the molding surface parallel to the opening / closing direction of the mold is discharged to the outside after being discharged to the dividing surface of the mold through the gas discharging channel. Even if the parallel molding surfaces face each other, the gas can be vented from both molding surfaces by intersecting the gas vent passages. At this time, in the gas vent passage, a waste pin is fitted on the surface of the die where the through hole is formed to form a narrow flow passage around the waste pin to prevent molten resin from entering. It can be easily constructed by striking the outer peripheral portion of a columnar member having substantially the same diameter as that of FIG.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an injection molding die of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a vertical sectional view of a mold showing a main part of the present invention, FIG. 2 is an enlarged view of a waste pin, FIG. 3 is a mold open state view, and FIG. 4 is a perspective view of a molded instrument panel.

The injection molding die of the present invention is configured for molding an instrument panel 20 which is an automobile interior component shown in FIG.
As described above, the box portion 21 includes four sides, that is, the left side surface portion 22, the right side surface portion 23, the upper surface portion 24, and the lower surface portion 25. The protruding edge portion of each side is bent inward. And inner flange portions 22a, 23a, 24a, 25a. Further, a rib 27 serving as a meter mounting seat is projected on the flange portion 25a of the lower surface portion 25 of the inner flange portion.

On the other hand, the gate 26 for injecting the molten resin is provided at one point in the center, but if the resin material has a good fluidity, it can be sufficiently filled from only this point, and it is advantageous in reducing the die manufacturing cost. That's why.

When molding the instrument panel 20 of such a form, the molten resin injected from the gate 26 spreads left and right, and the one facing the box portion 21 side is inward from the right side surface portion 23 close to the gate 26 side. It becomes a confluence part of the flow such as the one that reaches the left side surface part 22 through the flange part 25a, the one that reaches the left side surface part 22 through the lower surface part 25 from the right side surface part 23, and the inner flange part 25a.
A rib 27 is provided on the bottom of the rib 27, and a turbulent flow is likely to occur downstream of the rib 27. Therefore, the left side surface portion 22 is apt to accumulate gas.

As will be described later, the left and right side surfaces 2
Each side of the upper and lower surface portions 24 and 25 is parallel to the opening and closing direction of the mold when the mold is manufactured.
Since a, 23a, 24a, and 25a are along the dividing surface direction of the mold, it is impossible to effectively remove the gas from the left side surface portion 22 by the conventional method. Then, when the gas is solidified in a retained state, it becomes a defective portion 28, which is defective such as white streaks appearing on the surface of the molded product.

Now, the construction of the present invention for effectively venting the gas at such a portion will be described with reference to FIG. The mold 1 includes a movable mold 2 that molds the inner surface side of the box portion 21 and a fixed mold 3 that molds the outer surface side, and the movable mold 2 is configured as a male mold having a two-step protrusion 2a.
The fixed die 3 is configured as a female die having a two-step recess 3a (FIG. 3). Then, the movable mold 2 is opened to the left and right with respect to the fixed mold 3, and the mold can be closed and moved, and the cavity 6 is formed in the mold closed state as shown in the figure.

In the cavity 6, in the drawing, a horizontal molding surface 6a for molding the left side surface portion 22 of the instrument panel 20 is located below, and a horizontal molding surface 6b for molding the right side surface portion 23 is located above. The vertical molding surfaces 6c and 6d for molding the inner flange portions 22a and 23a are located on the left side. That is, the gate portion (not shown) is located above. Further, the horizontal molding surfaces 6a and 6b are parallel to the opening / closing direction of the mold.

The tip projection of the two-step projection 2a of the movable mold 2 and the recessed recess of the two-step recess 3a of the fixed mold 3 form an opening (a meter mounting hole for the box 21) in the molded product. Therefore, in the mold closed state, the tip convex portion and the depressed concave portion form a dividing surface (parting line) 7 that directly abuts each other.

On the other hand, in the mold of the movable mold 2, a plurality of cooling water passages 4 are provided, and an extruding pin 5 extending in the mold opening / closing direction is provided so as to be able to move forward and backward, and the tip end thereof has an inner flange portion 23a. It faces the cavity 6d to be molded.

A gas vent passage 10 is provided in the two-stage protrusion 2a of the movable die 2. This degassing channel 10 is
A circular through hole 11 having a diameter of about 1 cm is obliquely formed in the two-stage protrusion 2a. One end of this through hole 11 is opened on a horizontal molding surface 6a and the other end is open. The two-step protrusion 2a opens toward the side of the tip of the convex portion and communicates with the gas reservoir groove 12 formed at the position of the opening. That is, the gas reservoir groove 12 is provided, for example, along the mold opening / closing direction, has a depth of about 0.1 mm, and communicates with the vertical dividing surface 7 on the front surface.

On the other hand, a discarding pin 13 is fitted on the molding surface 6a side of the through hole 11. This discard pin 13
It serves as a stopper for preventing the molten resin from entering the through hole 11, and allows only gas to escape. That is, as shown in FIG. 2, the outer peripheral surface of a cylindrical steel material having a diameter substantially the same as or slightly smaller than that of the through hole 11 is strongly struck by a punch or the like to provide minute projections, and the outer periphery and the through hole 1 are provided.
The clearance C from the inner surface of the inner wall 1 is set to about 0.05 mm and is pushed into the through hole 11. And molding surface 6a
The end portion on the side is cut obliquely to be flush with the molding surface 6a.

The gas vent channel 10 has the through hole 1 as described above.
1, the gas reservoir groove 12, and the discard pin 13, the operation will be described. When the fixed mold 3 and the movable mold 2 are clamped and the molten resin is injected from the gate, the molten resin sequentially flows and is filled in the cavity 6. At this time, the gas stays on the molding surface 6a as described above, but this gas is directed from the clearance C between the through hole 11 and the discarding pin 13 of the gas vent channel 10 toward the gas reservoir groove 12. It is discharged and escaped from the gas reservoir groove 12 through the dividing surface. Therefore, there is no problem that the quality of the molding surface 6a is impaired. When the molding is completed and solidified, the mold is opened as shown in FIG.

Further, a plurality of the gas vent passages 10 as described above may be provided so as to vent the gas on the side of the other molding surface 6b at the same time. In this case, although not shown, the degassing flow paths are provided so as to intersect with each other, and both molding surfaces 6a, 6a
The gas from b can be removed to perform higher quality molding.

[0019]

As described above, in the injection mold of the present invention, the gas staying on the molding surface parallel to the mold opening / closing direction can be extracted to the outside of the cavity. It is possible to prevent problems such as incorrect accuracy. Further, the structure of the gas vent channel is as simple as providing a through hole and fitting the waste pin therein, and the waste pin can be easily manufactured.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a mold showing a main part of the present invention.

[Fig.2] Enlarged view of the waste pin

[Fig. 3] Mold open state diagram

FIG. 4 is a perspective view of a molded instrument panel.

[Explanation of symbols]

2 movable 3 fixed type 6a, 6b molding surface 7 division planes 10 degassing channel 11 through holes 12 gas reservoir groove 13 Discarded pin

Claims (4)

[Claims] 1. A mold in which gas is discharged from a molding surface that is substantially parallel to the opening / closing direction of the mold, and a gas vent passage communicating from the molding surface to the dividing surface of the mold is provided in one of the male and female molds. An injection molding die characterized by being provided. 2. The molding surface is provided so as to be opposed to each other at different positions, and a plurality of gas vent passages that connect the molding surface and the mold dividing surface are provided to intersect with each other. 1
The mold for injection molding according to. 3. The gas vent passage comprises a through hole connecting the molding surface and the dividing surface, a discarding pin provided at one end of the through hole on the molding surface side, and a gas reservoir groove formed on the dividing surface side of the mold. The mold for injection molding according to claim 1 or 2, wherein 4. The throwing pin is made of a columnar member having substantially the same diameter as the through hole, and the outer peripheral surface of the columnar member is struck by a punch or the like to form a dent and then fitted into the through hole. How to make a mold.