JP2894132B2 - Sandwich injection molding equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sandwich injection molding apparatus for molding a plurality of resins into a sandwich.

[0002]

2. Description of the Related Art Resin molded articles are molded by various methods in order to make full use of the properties of the resin and to satisfy the functions, shapes and production quantities required of the molded articles. The main method is, for example, an injection molding method for molding a thermoplastic resin such as a polypropylene resin into an automobile bumper, or a reaction injection molding (RIM) for a thermosetting resin such as a urethane resin.

[0003] In addition, instrument panels for automobiles.
There is an integral foam molding method for molding a molded product composed of a skin and a foam core material, such as a safety pad. Each of these molding methods uses one resin material as a material to be injected at the time of molding.

Recently, a multi-component injection molding method in which two or more types of materials are injected into one mold has been proposed from the viewpoints of enhancing the functionality of molded articles and effectively utilizing resin materials. It has been put to practical use for resin molded products.
This molding method can obtain a molded article slightly similar to the molded article obtained by the integral foam molding method, but differs in the method and the molded article structure in that the skin portion can be injection molded with a different resin material.

[0005] The above multi-component injection molding method comprises:
Since this is a method of molding a sandwich-like molded product by injecting a core material into a skin material, it is also called a sandwich molding method. The feature of this sandwich molding method is that the resin material used for the skin material has functions such as appearance and softness, and the core material has the function only as a filler, aiming at low cost and light weight. As mentioned above, this is a manufacturing method that shares functions and makes it possible to produce multifunctional products at low cost.

[0006] As shown in FIG. 6, a sandwich injection molding apparatus for performing the above-described molding uses a skin material 1 made of a resin material.
A first injection cylinder 11 for injecting the resin material, a second injection cylinder 21 for injecting the core material 2 as a resin material into the skin material 1, and a cavity 821 for molding the sandwich molded article 9 (FIG. 7). And a mold 8 having

The first injection cylinder 1 is mounted on the mold 8.
Runner 811 communicating with first and second injection cylinders 21
And a film gate 815 provided between the runner 811 and the cavity 821. The cavity 821 is formed by the split dies 81 and 82.
The film gate 815 is wide along the width direction of the cavity as shown in FIG.
It is as narrow as 5 mm (see FIG. 1 described later).

In molding the sandwich molded article, first, a required amount of the skin material 1 is injected into the cavity 821 of the mold 8, and then the core material is injected into the softened skin material 1. Inject 2. Then, these are cooled in the mold 8, and the sandwich molded product 9 (FIG. 7) is taken out.

By the way, when a bumper for an automobile is molded as a sandwich molded article by the above-mentioned conventional sandwich injection molding apparatus, the obtained sandwich molded article 9 is formed.
7 shows a state in which the core material 2 is injected into the skin material 1 as shown in FIG. And, as shown in FIG.
The entire gate width F of the film gate is injected into the skin material 1. Therefore, the core material 2 exists widely up to near both ends of the sandwich molded product 9.

In FIG. 7, an arrow indicates that the core material 2 is the skin material 1.
Shows the direction of travel when injected into the inside. Also,
Dotted lines 21 and 22 indicate the stages in which the core material 2 injected from the film gate sequentially advances in the skin material 1.
The core material 2 injected in this way pushes the skin material 1 in the depth direction of the cavity in order, and goes around the film gate to form a lateral intrusion portion 25.

In the case where the sandwich molded article is the above-mentioned bumper, since the surface portion is required to have an appearance and softness, a resin material having such a function is used as a skin material. However, on the other hand, since the core material is mainly required to function as a filler, there is a demand to use a material having low physical properties such as a recycled material.

[0012]

However, the sandwich molded article 9 for bumpers obtained by the conventional sandwich injection molding apparatus has the following problems. That is, as shown in FIG.
1 is in contact with a utility pole, a stone wall, or the like, so that the corner portion 91 is required to have flexibility.

Therefore, it is necessary to prevent the core material 2 from being injected into the corner portion 91. However, the sandwich molded article 9 obtained by the conventional apparatus is
As shown in FIG. 7, the core material 2 enters the corner. Therefore, it is required to prevent the core material from entering such unnecessary portions.

This is required not only for the above-mentioned automobile bumper but also for other sandwich molded products. SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a sandwich injection molding apparatus capable of injecting a core material only into a desired portion.

[0015]

The present invention comprises a plurality of injection cylinders for injecting a plurality of resin materials, respectively, and a mold provided with a cavity for molding a sandwich molded product. In a sandwich injection molding apparatus having a runner communicating with the injection cylinder and a film gate provided between the runner and the cavity, a resin material which enters the cavity by controlling the gate width of the film gate is provided. And a gate width control means for adjusting the injection distribution state of the injection molding.

The most remarkable point of the present invention is that the film gate is provided with a gate width control means for controlling the gate width to adjust the injection distribution state of the resin material. The gate width control means is provided in the film gate and basically has a function of closing or opening a part of the film gate. Further, the gate width control means may have a function of closing a part of the film gate in a half-open state. That is, the height of the film gate can be closed to half or one third.

The closing plate of the gate width control means is provided at an arbitrary place such as a side portion (FIG. 2), a center portion, and a side portion of the film gate depending on a required core material injection condition. The gate width control means preferably includes a closing plate for closing a part of the film gate, and an actuator for moving the closing plate back and forth. Examples of the actuator include a hydraulic actuator, a pneumatic actuator, and an electric actuator.

Further, a plurality of kinds of resin materials are used, for example, one for a skin material and one for a core material. Also,
A plurality of resin materials can be used for one or both of the skin material and the core material.

These resin materials are not particularly limited. For example, when the sandwich molded product is an automobile bumper, the skin material is polypropylene, polycarbonate (PC) / polybutylene terephthalate (PBT), polyamide, or the like. A resin material having excellent surface appearance and flexibility, such as (PA) / polyphenylene oxide (PPO) and urethane, is preferred. On the other hand, as the core material, it is preferable to use a recycled material for cost reduction.

Here, recycled materials are used,
It means that the resin, such as a defective product, is returned to pellets by crushing and re-melting, and used again as a resin material for injection.
For example, usually, when heat history during molding occurs, or when the original part is a resin bumper with a coating film, the crushed coating film pieces are dispersed in the resin, and the mechanical properties are low.

Therefore, as shown in FIG. 7, it is required that such recycled material is not injected into the corners of the bumper (see the above-mentioned conventional example). The core material is not only the above-mentioned recycled material,
A highly rigid material, a foamed material, or the like can also be used.

[0022]

In order to form a sandwich molded article by the sandwich injection molding apparatus of the present invention, first, a skin material as one resin material is injected into the cavity through a runner and a film gate in a softened state.
The volume of the skin material is filled halfway into the cavity in an amount necessary for forming the skin material. At this time, the gate width control means does not operate, and the film gate is in a state where all gate widths are opened.

Next, after the skin material is injected, the gate width control means is operated to control the gate width. After that, the core material as the other resin material is injected into the skin material. As a result, the skin material is pushed forward by the core material injected into the interior, and fills the cavity. Further, at this time, the skin material is cooled and solidified at the portion in contact with the wall surface of the cavity to form a skin material layer.

What is important in the present invention is that when the core material is injected, the gate width is controlled by the gate width control means, so that the core material is injected into the skin material from only a part of the film gate. Is to be done. Therefore, the distribution state of injection of the core material is adjusted.

Therefore, it is possible to obtain a sandwich molded product having a desired structure in which the core material is formed only in a part of the skin material. As described above, according to the present invention, it is possible to provide a sandwich injection molding apparatus capable of injecting a core material only into a desired portion. In this example, an example in which an automobile bumper is molded as a sandwich molded product will be described.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A sandwich injection molding apparatus according to an embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the sandwich injection molding apparatus of the present embodiment has a first injection cylinder 11 for injecting a skin material 1 as one resin material and a core material 2 for injecting a core material 2 as the other resin material. Second injection cylinder 21 and sandwich molded product 5
And a mold 4 provided with a cavity 421 for molding (FIG. 5).

The mold 4 includes the injection cylinders 11 and
1 and a film gate 41 provided between the runner 411 and the cavity 421.
And 5. The film gate 415 has a gate width control means 3 for controlling the gate width to adjust the injection distribution state of the core material 2 entering the cavity 421.

As shown in FIGS. 1 and 2, the gate width control means 3 has two closing plates 31 and 32 for closing both side portions of the film gate 415. A hydraulic cylinder 35 as an actuator is connected to the closing plates 31 and 32.

As shown in FIG. 1, the film gate 415 is located above and below the mold 4. Each film gate 415 has a pair of the closing plates 31 and 3 respectively.
2, a hydraulic cylinder 35 is provided. In FIG. 1, reference numeral 41 denotes an upper die, 42 denotes a lower die, and 417 denotes a sliding groove of the closing plates 31 and 32.

Next, the operation and effect of this embodiment will be described. In the present embodiment, a bumper for an automobile shown in FIG. Then, in the molding, as shown in FIG. 3, first, the closing plates 31, 32 of the gate width control means 3 are raised to bring all the film gates 415 into an open state.

Next, as shown in FIG. 3, the skin material 1 in the heat-softened state is applied to the runner 411 and the film gate 415.
And is injected into the cavity 421. Skin material 1
After a short shot by a predetermined amount, the hydraulic cylinders of the gate width control means 3 are operated to lower the closing plates 31 and 32 as shown in FIG. Control the gate width.

Next, as shown in FIG. 4, a core material 2 is injected into the softened skin material 1. At this time, the core material 2 is injected into the skin material 1 from the central portion of the sandwich molded product through the passage between the closing plates 31 and 32, the injection distribution state is adjusted.

The skin material 1 is pushed forward by the core material 2 injected into the inside thereof, and advances forward to fill the cavity 421. During this time, the cavity 4 in the skin material 1
The material that has contacted the wall surface of 21 is cooled and solidified to form a skin material layer of the bumper. Thus, as shown in FIG.
A bumper as the sandwich molded product 5 is obtained.

As shown in the figure, the sandwich molded product 5 comprises a long plate-shaped main body portion 51 having a U-shaped cross section, and protruding portions 52 protruding rearward on both sides thereof. 53. The sandwich molded product 5 has the core material 2 near the center of the main body portion 51, but does not include the core material 2 in the corner portion 53 and the projecting portion 52.

As shown in FIG. 5, when the core material 2 is injected, the closing plates 31 and 32 of the gate width control means 3 allow both sides S and S of the film gate to have a total gate width (S + G + S). This is because the core gate G was formed only during this time. That is, as shown by the dotted line in the figure, the core material 2 advances only near the center of the main body 51 of the sandwich molded product 5 and is not injected laterally.

In this example, polypropylene (PP) resin was used as the resin material for the skin material. As the resin material for the core material, a recycled material was used. This recycled material is obtained by crushing, re-melting, and pelletizing a molded product of a painted polypropylene resin, and its mechanical properties are inferior to those of a new resin.

In the bumper as the sandwich molded product 5 obtained in the present embodiment, the core material as the recycled material is not injected into the corner portion 53. Therefore, it is possible to obtain a low-cost bumper without a decrease in strength. As described above, according to the present embodiment, it is possible to provide a sandwich injection molding apparatus capable of injecting a core material only into a desired portion.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a sandwich injection molding apparatus in an embodiment.

FIG. 2 is a sectional view taken along line AA of FIG. 1;

FIG. 3 is an explanatory view at the time of injection of a skin material in the embodiment.

FIG. 4 is an explanatory view at the time of pouring a core material in the embodiment.

FIG. 5 is an explanatory view of a sandwich molded product in the embodiment.

FIG. 6 is an explanatory view of a conventional sandwich injection molding apparatus.

FIG. 7 is an explanatory view of a sandwich molded product obtained by a conventional example.

FIG. 8 is an explanatory view showing a problem of a sandwich molded product of a conventional example.

[Explanation of symbols]

 1. . . 1. skin material; . . Core material, 3. . . Gate width control means, 31, 32. . . Closing plate, 35. . . 3. hydraulic cylinder, . . Mold, 411. . . Runner, 415. . . Film gate, 421. . . Cavity, 5. . . Sandwich molded products,

Claims (2)

(57) [Claims] 1. A mold having a plurality of injection cylinders for injecting a plurality of resin materials, respectively, and a mold provided with a cavity for molding a sandwich molded product, and the mold communicates with the injection cylinder. And a film gate provided between the runner and the cavity. In the sandwich injection molding apparatus, the film gate has a gate width controlled to control the injection distribution state of the resin material entering the cavity. A sandwich injection molding apparatus provided with a gate width control means for adjusting. 2. A sandwich injection molding apparatus according to claim 1, wherein said gate width control means has a closing plate for closing a part of the film gate, and an actuator for moving the closing plate back and forth.