JPH08323805A - Manufacture of sound-insulating board - Google Patents

Abstract

PURPOSE: To prevent the voids included in a sound absorbing board from being collapsed by a method wherein fiber reinforced thermoplastic resin sheet is arranged in an injection mold and the gap in the mold is set under the condition that the expansion of the fiber reinforced thermoplastic resin sheet is taken into consideration. CONSTITUTION: On the cavity surface 1a of one of apair of injection molds 1 and 2, fiber reinforced thermoplastic resin sheet 3 having the thickness of (t). Next, at the communication with the mold 2, the gap A between a cavity surface 2a and the surface of its opposing fiber reinforced thermoplastic resin sheet 3 is set to the dimension, which is larger by the anticipated amount T-t of the expansion in the direction of the thickness of the fiber reinforced thermoplastic resin sheet 3 due to the heat of the injected synthetic resin material than the predetermined thickness dimension D of a backing board. When the synthetic resin material 4 is injected through the injection port 2b of the mold 2, the fiber reinforced thermoplastic resin sheet 3 having the thickness (t) expands through the application of the heat of the synthetic resin material 4 so as to form a sound absorbing board having the thickness T and the resin material 4 is formed into the backing board having the thickness D.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a sound insulation plate, which is formed by stacking a sound absorption plate and a support plate.

[0002]

2. Description of the Related Art In order to manufacture a sound insulating plate in which a sound absorbing plate and a supporting plate are superposed, a method of joining the supporting plate and the sound absorbing material by adhesion or the like is usually used.

[0003]

Since such a joining process is time-consuming, it has been attempted to manufacture a sound insulation plate by injection molding with a sound absorbing plate inserted therein by a simple construction method. In this case, the thickness of the sound absorbing plate is compressed by the injection pressure, and many air holes (air layers) included in the sound absorbing plate (often a non-woven fabric) are crushed, resulting in a very small sound absorbing effect. Will be things.

[0004]

[Means for Solving the Problems] A synthetic method of arranging a fiber reinforced thermoplastic resin sheet on a cavity surface of a mold for injection molding and injecting a void size in the mold to a predetermined thickness of a support plate. Set to a size that adds the expected size that the fiber reinforced thermoplastic resin sheet expands in the thickness direction due to the heat of the resin material,
This is a manufacturing method in which a synthetic resin material is injected into a mold cavity and the heat of the resin-reinforced thermoplastic resin sheet is expanded in the thickness direction to take out the product in the mold.

[0005]

With this manufacturing method, the fiber-reinforced thermoplastic resin sheet is expanded in the thickness direction by receiving the heat of the injected synthetic resin material. In this case, the expansion of the fiber reinforced thermoplastic resin sheet means that when the resin is heated to near the melting point by heat and becomes a semi-molten state, the entanglement of the fibers compressed in the entangled state is loosened and expanded in the thickness direction. It means being in a state. In this way, the fiber-reinforced thermoplastic resin sheet is increased in thickness, bubbles are generated inside, and the fiber-reinforced thermoplastic resin sheet is in a porous state to obtain a tissue structure as a sound absorbing material.

[0006]

EXAMPLE An example will be described with reference to FIGS. On one cavity surface 1a of the pair of molds 1 and 2 for injection molding,
A fiber reinforced thermoplastic resin sheet 3 (in this example, a glass fiber reinforced polypropylene sheet, thickness t) is set. When combining the molds 2 as shown in FIG. 1 (b),
The gap A between the cavity surface 2a and the surface of the fiber-reinforced thermoplastic resin sheet 3 which faces the cavity surface 2a is arranged in a predetermined thickness dimension D of the support plate (FIG. 2 (b)). It is set to a size obtained by adding an expected size {(T−t), see FIG. 2 (b) T} in which the injected synthetic resin material expands in the thickness direction due to heat.

As shown in FIG. 2A, a synthetic resin material 4 (polypropylene in this example, other materials such as polyamide may be used) is injected from an injection port 2b of a mold 2.
The heat of the synthetic resin material 4 causes the fiber-reinforced thermoplastic resin sheet 3 having a thickness t to expand to form a sound absorbing plate 5 having a thickness T (FIG. 2), and the resin material 4 has a supporting plate having a thickness D. It becomes 6. That is, the breakdown of the distance between the cavity surfaces 1a to 2a is (t +
A) → (T + D). When this product is taken out of the molds 1 and 2, a sound insulating plate 7 (FIG. 2 (b)) in which a sound absorbing plate (thickness T) and a supporting plate (thickness D) overlap each other is obtained.

[0008]

According to the manufacturing method of the present invention, the fiber-reinforced thermoplastic resin sheet is arranged in the mold for injection molding, and the expansion of the fiber-reinforced thermoplastic resin sheet is expected in the voids in the mold. A sound insulating plate in which a sound absorbing plate and a supporting plate overlap each other can be obtained only by an extremely simple injection molding process.

[Brief description of drawings]

FIG. 1 is a diagram showing a first half process of an example.

FIG. 2 is a diagram showing a second half of the process of the example.

[Explanation of symbols]

 1, 2 Mold 3 Fiber reinforced thermoplastic resin sheet 4 Synthetic resin material 5 Sound absorption plate 6 Support plate

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Claims (1)

[Claims] 1. A method for manufacturing a sound insulation plate in which a sound absorbing plate and a supporting plate are superposed on each other, wherein a fiber reinforced thermoplastic resin sheet is arranged on a cavity surface of an injection molding die, and a void size in the die is adjusted. The synthetic resin material is injected into the mold cavity by setting the dimension that the fiber-reinforced thermoplastic resin sheet expands in the thickness direction due to the heat of the synthetic resin material to be injected and the expected dimension is added.
A method for manufacturing a sound insulating plate, wherein a fiber-reinforced thermoplastic resin sheet is expanded in a thickness direction by heat of a synthetic resin material and a product in a mold is taken out.