JPS63309416A - Vacuum drawing injection molding device - Google Patents

Abstract

PURPOSE:To prevent defective molding such as a void from occurring by preventing staying of air or expandable gas to be generated within a mold by absorbing the same immediately, by a method wherein a seal member is provided on the surface of a bottom force at a part of the circumference of a vacuum drawing hole and a porous body is fixed to a position facing on the seal member of the inside of an insert member further. CONSTITUTION:Air within a cavity 5 is sucked through a vacuum drawing hole 8 provided on the top of a bottom force 3 and mold clamping is performed by performing mold register of a top force 1 and the bottom force 3 through cores 6, 7 while vacuum drawing is started. In this instance, as a seal member 9 and skin member 4 provided on the bottom force 3 are stuck close to each other, a urethane solution 13 which has flowed out into a gap between the bottom force 3 and skin member 4 through the vacuum drawing hole 8 is prevented from adhering to the surface of a product. When the air and expandable gas which are staying within the urethane solution 13 are sucked through the vacuum drawing hole 8 after the top and bottom forces 1, 3 have been made into a sealed state, a porous body 10 stuck to the inside of the insert member 2 abuts against a small hole or slit 4a formed on the skin member 4 by communicating with the vacuum drawing hole 8. Therefore, the air and expandable gas within the urethane solution 13 are sucked through the vacuum drawing hole 8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a vacuum injection molding apparatus, and particularly to an injection molding apparatus suitable for molding instrument panel safety pads and the like installed in automobiles.

[Conventional technology]

In reaction injection molding for molding instrument panel safety pads etc. installed in automobiles.

Conventionally, an injection molding apparatus as shown in FIG. 4 has been used.

That is, an insert member 2 is attached to the lower surface of the upper mold 1, a skin member 4 is attached to the upper surface of the lower mold 3, and a material such as urethane is placed between the insert member 2 and the skin member 4. A cavity 5 is formed into which the molding raw material is injected. Further, a core 6.7 for undercut processing is provided at the abutting portion between the upper mold 1 and the lower mold 3.

In the conventional injection molding apparatus configured as described above,
If the shape of the molded product is complex or large, molding defects are likely to occur, reducing productivity. This molding defect is caused by injecting a foamable molding material such as urethane into the lower mold 3 with the molds 1 and 3 open, and then when the molds 1 and 3 are closed, the urethane foams and flows into the cavity 5. However, the air and foaming gas inside the mold accumulates in areas with uneven surfaces, such as those shown in Figure 1A, and this air and foaming gas gets caught up in the urethane, creating so-called voids. Missing parts may occur, resulting in poor appearance.

As a means to solve this problem,
As disclosed in Japanese Patent No. 68212, a parting surface of the mold adjacent to the end of the cavity is communicated with the cavity to form a relief part for the molding material, and the relief part is further connected to an external vacuum via an exhaust passage. Molding apparatuses are known in which a pulling device is connected to create a complete vacuum at the end of the cavity so that this part is fully filled with molding material.

[Problem that the invention seeks to solve]

However, the proposal disclosed in the above publication is effective in removing air and foaming gas at the end of the cavity and sufficiently filling that part with molding raw material, but it If there are irregularities or openings, no consideration has been given to a means for discharging the air or foaming gas that remains because the leading edge of the flow of the forming raw material joins this region from this region.

As a result, there is a problem in that air or foaming gas is drawn into the molded product at this location, causing molding defects such as voids.

The present invention was made in view of the above circumstances, and prevents the accumulation of air and foaming gas around the terminals and openings in the mold.
An object of the present invention is to provide a vacuum injection molding apparatus that can prevent molding defects such as voids from occurring.

[Means for solving problems]

In order to achieve the above object, the present invention discharges the gas in the cavity formed between the insert member attached to the upper mold and the skin member attached to the lower mold to the outside of the mold by vacuuming. , in a vacuum injection molding apparatus for injection molding a molding raw material, a vacuum hole passing through the skin member is provided in the lower mold in a region where gas concentrates and stays in the cavity, and a vacuum hole is provided around the vacuum hole. A sealing member for blocking the cavity between the skin and the lower mold is provided on the surface of the lower mold, and a porous body is provided on the inner surface of the insert member at a position facing the sealing member so as to be able to come into contact with the skin member. It is constructed by attaching.

[Effect]

According to the above configuration, a vacuum hole is provided in the lower part of the cavity where there are unevenness and openings where the flow of molding raw materials is slow and air and foaming gas tend to accumulate, so only the gas in this area is removed from the insert. Vacuum is drawn through the porous body attached to the member and the penetration portion formed in the skin member.

At this time, the porous body prevents the molding material from being sucked into the vacuum hole, and the sealing member provided on the lower mold allows the molding material to flow from around the vacuum hole between the skin member and the lower mold. This prevents it from getting onto the product surface.

〔Example〕

Hereinafter, one embodiment of the vacuum injection molding apparatus according to the present invention will be described with reference to two aspects.

An embodiment of the present invention is shown in FIGS. 1, 2, and 3.
In the figure, parts that are the same or equivalent to those of the conventional example shown in FIG. 4 are designated by the same reference numerals, and their explanation will be omitted.

The feature of this embodiment is that a vacuum hole 8 communicating with the cavity 5 is provided in the lower mold 3 at a position opposite to the area where the uneven portion of the product is formed, and the surface of the lower mold 3 around the vacuum hole 8 is provided. A seal member 9 is provided on the insert member 2, and a porous body 10 made of urethane slab or the like is bonded to the surface of the insert member 2 at a position facing the seal member 9 so as to be able to come into contact with the skin member 4.

Further, a small hole or slit 4a is formed in the skin member 4 at a position aligned with the vacuum hole 8, and the vacuum hole 8 and the cavity 5 are communicated with each other. code 11
is a vacuum hole formed in the lower mold 3 for vacuum suction in order to prevent the lower mold 3 and the skin member 4 from shifting and to leave the product in the lower mold 3 when the mold is opened. Further, reference numeral 12 is a vacuum hole for exhausting the entire gas inside the lower mold 3 to the outside.

Next, the operation of this embodiment configured as described above will be explained.

First, as shown in FIG. 2, the insert member 2 and the skin member 4 are attached to the upper mold 1 and the lower mold 3 respectively in the mold open state, and the molding raw material is placed in the recess of the skin member 4 attached to the lower mold 3. Inject urethane liquid 13.

Next, the vacuum hole 12 provided at the bottom of the lower mold 3 is connected to a vacuum pump (not shown), and the air in the cavity 5 is sucked through the vacuum hole 8 provided on the top surface of the lower mold 3. hand,
While starting vacuuming, insert upper mold 1 and lower mold 3 into core 6.7.
The mold is then clamped to form the state shown in FIGS. 1 and 3.

At this time, since the sealing member 9 provided on the lower mold 3 and the skin member 4 are in close contact with each other, the urethane liquid 13 flowing out from the vacuum hole 8 into the gap between the lower mold 3 and the skin member 4 is released into the product. Prevents it from adhering to surfaces.

In addition, when air or foaming gas remaining in the urethane liquid 13 is sucked through the vacuum hole 8 after the upper mold 1 and the lower mold 3 are sealed, the inner surface of the insert member 2 is bonded. Since the porous body 10 communicates with the vacuum hole 8 and contacts the small hole or slit 4a formed in the skin member 4, air and foaming gas in the urethane liquid 13 are sucked by the vacuum hole 8. However, the urethane liquid 13 is not sucked into the vacuum hole 8.

According to this embodiment, air and foaming gas that accumulate around the uneven parts of a molded product such as an instrument panel safety pad are removed from the lower mold 3.
It is possible to suction through the vacuum hole 8 provided in the mold and sufficiently evacuate the air outside the mold, thereby preventing defects such as voids from occurring in the product.

Moreover, the sealing member 8 provided on the lower die 3 and the porous body 10 bonded to the insert member 2 can prevent the urethane liquid 13 from adhering to the product surface and into the vacuum hole 8 or being inhaled. or damage the vacuum pump.

In the above-mentioned embodiment, a case was explained in which vacuum holes 8 were especially provided near the uneven portions of the molded product.

If a vacuum hole 11 provided in the lower mold 3 for suction-fixing the skin member 4 to the lower mold 3 is located near the uneven portion, the vacuum hole 11 can be used to remove air or foam that remains near the uneven portion. It may also be used for gas suction.

Further, the location where the vacuum hole 8 is provided is not limited to the uneven portion of the molded product, and may be located at a location such as another opening where air or foaming gas tends to accumulate. Furthermore, the molding raw material is not limited to the urethane liquid 13, and similar effects can be obtained when other foaming materials are used.

In the above embodiment, the case where the upper mold 1 and the lower mold 3 are opened and the molding material is injected between them is explained, but the molding material is injected into the gap between the upper mold 1 and the lower mold 3 through a separately provided injection port, and vacuum is drawn. The same is true.

〔Effect of the invention〕

As described above, according to the present invention, a vacuum hole is provided in the lower mold in the region where gas is concentrated in the cavity of the vacuum injection molding apparatus, and a sealing member is provided on the surface of the lower mold in the region around the vacuum hole. In addition, a porous body was installed on the inner surface of the insert member at a position opposite to this sealing member, so the air and foaming gas generated in the mold were immediately sucked in, preventing them from accumulating.
It is possible to prevent molding defects such as voids from occurring.

Moreover, this suction does not contaminate the surface of the product with molding raw materials, nor does it damage the vacuum pump for evacuation.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing an embodiment of a vacuum injection molding apparatus according to the present invention, and FIGS. 2 and 3 are enlarged longitudinal cross-sectional views of essential parts showing the operation of this embodiment, respectively. FIG. 4 is a longitudinal sectional view showing a conventional vacuum injection molding apparatus. 1... Upper mold, 2... Insert member. 3...Lower mold, 4...Skin member. 5...Cavity, 8, 11.12...Vacuum hole. 9... Seal member, 10... Porous body, 13...
... Urethane liquid (molding raw material).

Claims (1)

[Claims] Vacuum injection molding, in which the gas in the cavity formed between the insert member attached to the upper mold and the skin member attached to the lower mold is ejected outside the mold by vacuuming, and the molding material is injected. In the apparatus, a vacuum hole passing through the skin member is provided in the lower mold in a region where gas concentrates and stays in the cavity, and a skin and a lower mold are provided on the surface of the lower mold around the vacuum hole. A vacuum injection injection device characterized in that a sealing member is provided to block the cavity between the spaces, and a porous body is attached to the inner surface of the insert member at a position facing the sealing member so as to be able to come into contact with the skin member. Molding equipment.