JP3845556B2 - Synthetic resin foam molding method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for molding a synthetic resin foam molded article.
[0002]
[Prior art]
For example, there is a door trim as a synthetic resin foam molded product for automobile parts. In this conventional molding method, as shown in FIG. 3, a fixed mold 1 having an injection passage 2 of a synthetic resin foam base material and a combined mold of a movable mold 3 that contacts and separates from the fixed mold 1 are used. 3A, the movable mold 3 is moved closer to the fixed mold 1 as shown in FIG. 3B, and the synthetic resin foam base material 4 is moved from the injection passage 2 to the fixed mold 1 and the movable mold 3 as shown in FIG. And the press is started. As shown in FIG. 3C, the movable mold 3 is matched with the fixed mold 1 and the synthetic resin foam base material 4 is subjected to primary pressurization. Spreading to every corner of the gap 5 to be a molded product, and slightly opening the movable mold 3 as shown in FIG. 3D, the pressure inside the mold is lowered, and the foaming action of the synthetic resin foam base 4 is promoted. A synthetic resin foam molded article 6 is molded, and the movable mold 3 is again brought into contact with the fixed mold 1 and subjected to secondary pressurization as shown in FIG. The molded synthetic resin foam molded product 6 is shaped, and the synthetic resin foam molded product 6 is shaped by moving the movable mold 3 away from the fixed mold 1 as shown in FIG. 3 (A). Demolded.
[0003]
[Problems to be solved by the invention]
Synthetic resin foam moldings have parts that require strength and rigidity. For example, in the door trim described above, a speaker grill part, a clip seat part, a boss part, a heat caulking part, and the like that transmit the sound of a speaker installed in the door are parts that require strength such as impact. However, in the conventional synthetic resin foam molding method, since foaming is performed as a whole including the parts where these strengths are required, the mesh 7 for transmitting the sound of the speaker as shown in FIG. Foams and the impact resistance decreases. In addition, while the weight can be reduced by foaming, there are problems such as a decrease in acoustic performance and a reduction in space because the thickness is increased to ensure rigidity. In addition to the speaker grille, there is a problem in that impact resistance is reduced, torque of the screw is reduced, and space is reduced.
[0004]
An object of the present invention is to provide a synthetic resin foam molding method capable of simultaneously integrally molding a portion requiring strength and rigidity in a synthetic resin foam molded article.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a synthetic resin foam molding method in which a synthetic resin foam base material is injected and foam-molded into a combined mold of a fixed mold and a movable mold. A pressing member capable of moving back and forth into the mating mold is provided in a fixed mold at a site that requires the strength and rigidity of the foam molded product, and the movable mold is slightly placed during foam molding of the synthetic resin foam base material injected into the mating mold. to open by pressing the foam molded article partially to the forward movement of the pressing member with lowering the mating mold internal pressure and is characterized in that so as to suppress the portion of the foam.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, using a fixed mold 1 having an injection passage 2 of a synthetic resin foam base and a movable mold 3 that contacts and separates from the fixed mold 1 is a conventional method. It is the same. In the present invention, the fixed mold 1 is provided with a pressing member 8 capable of moving back and forth in the mold at a portion requiring the strength and rigidity of the foam molded product. For example, a hydraulic cylinder (not shown) is suitable as the advance / retreat operation device for the pressing member 8, but the invention is not limited to this.
[0007]
The synthetic resin foam molding process using the fixed mold 1 and the movable mold 3 provided with the pressing member 8 as described above is shown in FIG. As shown in FIG. 1B, the movable mold 3 is brought close to the fixed mold 1 and the synthetic resin foam base material 4 is injected between the fixed mold 1 and the movable mold 3 from the injection passage 2 to start pressing. ), The movable mold 3 is matched with the fixed mold 1 and the synthetic resin foam base material 4 is primarily pressurized to spread the synthetic resin foam base material 4 to every corner of the gap 5 to be a molded product.
[0008]
The steps up to here are the same as in the conventional method, but the next step is the point of the present invention. That is, as shown in FIG. 1D, the movable mold 3 is slightly opened to lower the pressure in the mold and promote the foaming action of the synthetic resin foam base material 4 to form the synthetic resin foam molded article 6. At this time, the pressing member 8 is moved forward into the mold and a part to be foamed is pressed by the pressing member 8 to suppress foaming.
[0009]
In FIG. 1 (D), the synthetic resin foam molded product 6 formed by suppressing part of foaming is again brought into contact with the movable mold 3 and the secondary pressure is applied as shown in FIG. 1 (E). After that, the synthetic resin foam molded product 6 that has been molded is shaped, and the movable mold 3 is shaped away from the fixed mold 1 as shown in FIG. The molded product 6 is removed from the mold.
[0010]
For example, in the case of a door trim having a speaker grill portion, the synthetic resin foam molded product 6 thus molded has a configuration in which foam 9 is suppressed by pressing the mesh 9 of the speaker grill portion with a pressing member 8 as shown in FIG. Molded, thin and yet rigid.
[0011]
In the case of a door trim in such a manner, strength such as impact resistance can be ensured by suppressing foaming by pressing the clip seat portion, the boss portion, the heat caulking portion and the like other than the speaker grille portion with the pressing member 8. Incidentally, when the Izod impact value of the synthetic resin foam molded product with foaming and without foaming was compared, as shown in FIG. 5, the Izod impact value index was 33% at the test temperature of 23 ° C. with foaming but 100 with no foaming. %, 27% with foaming at a test temperature of −30 ° C., but 63% without foaming.
[0012]
The foaming of the synthetic resin foam base material according to the present invention is a method of heating and foaming the synthetic resin foam base material injected into the mold by heating the mold or a foaming agent is mixed in the synthetic resin foam base material and the synthetic resin in the mold The present invention can be applied to any method in which the foam base material itself foams. The foamed synthetic resin material is not particularly limited, such as polypropylene or polyurethane.
[0013]
Further, FIG. 1 shows an embodiment in which a synthetic resin foam base material 4 is injected into a mold and pressed in a state where the mold is opened. In this case, there is an advantage that the synthetic resin foam base material 4 is spread to every corner of the gap 5 of the mating die where the synthetic resin foam base material 4 becomes a molded product by pressing the synthetic resin foam base material 4. The present invention is also established by a method in which the synthetic resin foam base material 4 is injected at a high pressure into the gap 5 that becomes a molded product.
[0014]
【The invention's effect】
As described above, according to the present invention, it is possible to suppress foaming of a part that requires the strength and rigidity of a synthetic resin foam molded article by a simple method, and to perform integral foam molding with the part, and to provide strength such as impact resistance. A secured synthetic resin foam molded article can be provided.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of steps of a molding method of the present invention. FIG. 2 is a cross-sectional view showing an example of a synthetic resin foam molded article molded by the method of the present invention. FIG. 4 is a cross-sectional view showing an example of a synthetic resin foam molded article molded by a conventional method. FIG. 5 is a comparison of impact strength between the method of the present invention and a synthetic resin foam molded article molded by a conventional method. Chart [Description of symbols]
DESCRIPTION OF SYMBOLS 1 Fixed type | mold 2 Injection path | route 3 of synthetic resin foam base material Movable type | mold 4 Synthetic resin foam base material 5 Gap | interval used as a molded article 6 Synthetic resin foam molded article 8 Pressing member

Claims (1)

In the synthetic resin foam molding method of foam molding by injecting a fixed and the foamed synthetic resin base material combined type in accordance with the movable die, the strength of the foamed molded article of the forward and backward movable pressing member to the mating type in said stationary die -Provided in a portion requiring rigidity, and when the synthetic resin foam base material injected into the mating mold is foamed, the movable mold is slightly opened to lower the pressure in the mating mold and move the pressing member forward. synthetic resin foam molding method, wherein a foam molded article was partially pressed and to suppress the portion of the foam.

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