JP3736752B2 - Manufacturing method of foam molded article with good appearance quality - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a foam-molded article having good appearance quality used for automobile interiors and the like.
[0002]
[Prior art]
Foam molded products are often used for automobile interior parts such as door trims and dashboards, and in such automobile interior parts, the surface of the molded product is covered with a finishing material when used for high-grade vehicles. The appearance quality of the surface will not be a problem, but for those used in inexpensive vehicles, it is common to leave the molded skin without covering the surface except for some ornamental parts etc. from the viewpoint of cost The appearance quality is important.
[0003]
In a conventional method for molding foamed molded products, a valve gate that opens and closes the communication port between the hot runner and the cavity is opened by an open signal from the molding machine, and the opening of the valve gate is confirmed on the molding machine side. The resin is injected from the molding machine, and a foamed molded product is molded in the cavity. For this reason, there will be a delay time between the release of the valve gate and the injection of the resin from the molding machine. Even before the resin is injected from the molding machine, the resin is discharged by the foaming pressure simultaneously with the opening of the valve gate. It was injected into the cavity.
[0004]
FIG. 3 shows the change in the rate at which the resin is injected into the cavity. When the valve gate is opened at the point A, the resin is injected into the cavity by the foaming pressure, and the valve gate is opened by the molding machine. As a result of the confirmation, injection of the resin starts at time B. In such a series of processes, as shown in FIG. 4, the resin injected into the cavity is first cooled by the foaming pressure to form a skin layer, and then the resin injected from the molding machine is injected into the cavity. Then, as shown in FIG. 5, the skin layer is deformed by the injected resin, and the deformation of the skin layer produces a ring-shaped mark on the gate portion, which has a problem of deteriorating the appearance quality of the molded product.
[0005]
[Problems to be solved by the invention]
The present invention has been made in order to solve the above-described problems and to provide a method for producing a foam-molded article having a good appearance quality in which a ring-shaped mark generated around a gate is not generated.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the manufacturing method of a foam molded article with good appearance quality according to the present invention is a signal from a valve gate that opens and closes a communication port between a hot runner and a cavity. In the method of manufacturing a foam molded article in which injection is started, the cavity is composed of a main cavity for the molded article and a disposal cavity, and separate valve gates are provided at the communication ports of both the cavity and the hot runner, First, the valve gate of the waste cavity is opened and resin injection is started from the molding machine. After filling of the resin into the waste cavity starts, the valve gate of the main cavity is opened to fill the main cavity with resin and perform foam molding. It is characterized in that the product is molded.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows an example of a mold used when carrying out the method of manufacturing a foamed molded article having good appearance quality according to the present invention, which is provided with a main cavity 1 for molding the molded article and a disposal cavity 2. The main cavity 1 is provided with main cavity valve gates 3 and 3, and the waste cavity 2 is provided with a waste cavity valve gate 4. The valve gates 3 and 3 and the valve gate 4 are opened and closed by the operation mechanisms 5 and 5 and the operation mechanism 6, and hot for guiding the resin supplied from the molding machine to the valve gates 3 and 3 and the valve gate 4. A runner 7 is provided. Although not shown, it goes without saying that a mold opening / closing mechanism, a mold clamping mechanism, a molded product discharge mechanism, etc. are provided, but this point is not different from that in a conventional apparatus of this type. Omitted.
[0008]
The operation mechanisms 5, 5 and 6 of the valve gates 3, 3 and 4 are individually adapted to receive operation signals from a molding machine (not shown), and the operation mechanisms 5, 5 or 6 operate according to the operation signals from the molding machine. When the valve gate 3, 3 or 4 is opened, an opening confirmation signal for each valve gate 3, 3 or 4 is returned to the molding machine.
[0009]
In such a configuration, the molding machine first gives a signal to the operation mechanism 6 from the molding machine, and the operation mechanism 6 opens the valve gate 4 for the disposal cavity. FIG. 2 shows changes in the rate at which the resin is injected into the main cavity 1 and the waste cavity 2. When the valve gate 4 for the waste cavity is opened at the point A, the resin in the hot runner 7 is shown. Is injected into the waste cavity 2 from the valve gate 4 for the waste cavity due to the foaming pressure. Then, when the molding machine confirms the release of the valve gate 4 for the cavity, resin injection starts at the point B, and subsequently, a signal is given from the molding machine to the operation mechanisms 5 and 5 to send the main cavity. The resin valve gates 3 and 3 are opened, and the resin injected into the hot runner 7 is injected into the main cavity 1 from the valve gates 3 and 3 for the main cavity.
[0010]
Thus, in the conventional method, as described above, the resin first injected into the cavity by the foaming pressure forms a skin layer, and the deformation of the skin layer reduces the appearance quality of the foam molded product. In the invention, the resin is first injected from the valve gate 4 for the discarded cavity into the discarded cavity 2 by the foaming pressure, and is not suddenly injected into the main cavity 1. The product is not formed with the deformed skin layer, and there is no possibility that the appearance quality is deteriorated. The resin injected into the discard cavity 2 may be reused together with the resin left in the hot runner 7 and the like.
[0011]
In the above-described embodiment, a mold in which the main cavity 1 and the disposal cavity 2 are provided independently is used. However, a portion that does not cause a problem in appearance quality such as a portion to which an ornament is attached is simultaneously purified. In some cases, the cavity corresponding to the ornament sticking part may be used as a discarding cavity. In such a case, the resin molded in the discarding cavity part can be used as it is without being recycled.
[0012]
【The invention's effect】
As described above, the present invention provides a method for manufacturing a foam molded product in which injection from a molding machine to a mold is started by a signal from a valve gate that opens and closes a communication port between a hot runner and a cavity. A separate valve gate is provided at the communication port between the two cavities and the hot runner as a main cavity for the product and a disposal cavity. First, the valve gate of the disposal cavity is opened and resin is injected from the molding machine. After the start and filling of the resin into the waste cavity started, the valve gate of the main cavity was opened and the main cavity was filled with resin to form a foam molded product, so the molded product molded in the main cavity The appearance quality is not deteriorated.
Therefore, the present invention contributes greatly to the industry as providing a method for producing a foam molded article with good appearance quality that solves all the conventional problems.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of a mold used in carrying out the present invention.
FIG. 2 is a view showing a change in a rate at which resin is injected into a cavity when molding is performed by the molding method of the present invention.
FIG. 3 is a diagram showing a change in a rate at which resin is injected into a cavity when molding is performed by a conventional molding method.
FIG. 4 is a cross-sectional view showing a state where a resin is injected by foaming pressure when molding is performed by a conventional molding method.
FIG. 5 is a cross-sectional view showing a state in which a resin is injected by injection when molding is performed by a conventional molding method.
[Explanation of symbols]
1 Main cavity 2 Waste cavity 3 Valve gate 4 Valve gate 7 Hot runner

Claims (1)

In a method of manufacturing a foamed molded article in which injection from a molding machine to a mold is started by a signal from a valve gate that opens and closes a communication port between the hot runner and the cavity, the cavity is divided into a main cavity for the molded article, a waste cavity, As an alternative, a separate valve gate is provided at the communication port between both cavities and the hot runner. First, the valve gate of the disposal cavity is opened, and the injection of resin from the molding machine is started. A method for producing a foam-molded article with good appearance quality, wherein after the filling starts, the valve gate of the main cavity is opened to fill the main cavity with resin to form a foam-molded article.

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