JPH06305343A - Instrument panel core for vehicle and molding method thereof - Google Patents

Abstract

PURPOSE:To provide a molding method of an instrument panel core for vehicle in which the load bearing ability is sufficient and the core surface is provided with reinforcing ribs to eliminate generating shrinkage deformation. CONSTITUTION:When melting thermoplastic resin is injected into the cavity 25 of a metallic mold 20 so as to injection-mold an instrument panel core for vehicle having reinforcing ribs on the back, a flow passage rib-likely recessed into triangular section is formed on the cavity face at the part position forming the reinforcing ribs thereon, high pressure gas or foaming gas are injected into the flow passage in the cavity 25 after injecting the molten thermoplastic resin, and the molten thermoplastic resin in the flow passage is pressed against the wall face of the flow passage so as to form reinforcing ribs having cavity parts therein.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle instrument panel core and a method for molding the same.

[0002]

2. Description of the Related Art An instrument panel for a vehicle is provided inside a lower end of a windshield and is provided with an instrument panel, a ventilation port of an air conditioner, and the like. This instrument panel is often used in which a resin core is used as a core material, and a skin is laminated on the surface of the core via a cushioning material.

The instrument panel, which is arranged to fill the width of the vehicle compartment and has a laterally long shape, is easily deformed by the weight of the instrument panel or the like. Therefore, conventionally, in order to prevent the deformation, a reinforcing rib is erected on the back surface of the instrument panel core along the lateral direction (longitudinal direction) to increase the rigidity. The reinforcing ribs are preferably provided in the direction perpendicular to the core surface from the viewpoint of load resistance.

However, in general, a resin molded product shrinks due to natural cooling after molding. Therefore, if there is a partial thickness change in the molded product, a difference in shrinkage occurs, and the surface of the molded product is liable to be deformed such as a sink mark. Therefore, in the case where the reinforcing rib is provided as in the instrument panel core, the rib portion has a large wall thickness, so that a difference in contraction occurs between the rib portion and other normal thickness portions, and the surface is deformed. It is likely to occur and the appearance of the product may be impaired.

The instrument panel core is molded by injection molding in which a molten thermoplastic resin is injected into a cavity of a mold and the molded product is released from the mold after being cured in view of molding workability and quality obtained. It is often done.
However, since the mold used for molding the instrument panel core is usually a split mold structure in which a convex mold with a convex mold surface and a concave mold with a concave mold surface are opened horizontally or vertically, Depending on the position and orientation of the ribs formed on the instrument panel core, the ribs may be undercut and may be damaged during demolding.

Particularly, when ribs are provided perpendicularly to the core surface along the lateral direction of the instrument panel core, the ribs 42 are under the mold opening direction as shown in the mold sectional view of FIG. The cut shape 44 (chain line portion) was formed, and the above-mentioned problems were likely to occur. On the other hand, when the ribs 46 are provided in parallel with the mold opening direction to prevent the undercut shape, there arises a problem that sufficient load resistance cannot be obtained. Furthermore, when the substantially triangular thick portion 48 is provided as a rib so as not to generate an undercut shape as shown in FIG. 12, when the thick portion 48 and other normal thickness portions are contracted after demolding. The difference becomes even larger, and deformation due to it becomes more likely to occur.

[0007]

In view of the above-mentioned problems, the present invention has an instrument panel core for a vehicle having a reinforcing rib which has a sufficient load bearing capacity and which does not cause shrinkage deformation on the core surface. It is intended to provide the molding method.

[0008]

According to a first aspect of the present invention, in a vehicle instrument panel core made of resin having a reinforcing rib on the back surface, the rib has a hollow portion inside.

A second aspect of the present invention is a method for injecting a molten thermoplastic resin into a cavity of a mold to injection-mold an instrument panel core for a vehicle having a reinforcing rib on the back surface, wherein the reinforcing rib is formed. A cavity is formed in the cavity surface of the part in the shape of a rib with a substantially triangular cross section, and after injection of the molten thermoplastic resin, high-pressure gas or foaming gas is injected into the cavity inside the cavity to melt the inside of the cavity. It is characterized in that a thermoplastic resin is pressed against the wall surface of the flow path to form a reinforcing rib having a hollow portion inside.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings. 1 is a perspective view of an instrument panel core according to an embodiment of the present invention, FIG. 2 is a 2-2 sectional view thereof, FIG. 3 is a 3-3 sectional view thereof, and FIG. 4 is used for a molding method of the present invention. FIG. 6 is a sectional view corresponding to a section 4-4 in FIG. 1, FIG. 5 is a sectional view of a mold corresponding to a section 2-2 in FIG. 1, and FIG. 6 is a section 3-3 in FIG. Sectional view of the die corresponding to the section, FIG. 7 is an enlarged sectional view showing the vicinity of the die groove portion at the time of injection, FIG. 8 is an enlarged sectional view showing the vicinity of the die flow path portion at the time of injection, and FIG. FIG. 10 is an enlarged cross-sectional view showing the vicinity of the die groove portion of FIG. 10, and FIG.

Instrument panel core 1 shown in FIG.
No. 0 is injection-molded by the method of the present invention, and has a horizontally long shape in which holes for the instrument panel, the air vent of the air conditioner, etc. are formed at predetermined positions. 12 parts shown by a chain line show the runner part cut off after molding.

The instrument panel core 10 is
It is made of a thermoplastic resin such as acrylonitrile-styrene and has a plurality of ribs 14 formed on the back surface along the lateral direction. The rib 14 is, as shown in FIG.
A cross section orthogonal to the lateral direction has a triangular shape and has a hollow portion 15 at the center of the inside. The plurality of ribs 14 are connected at a predetermined position to a ridge 16 extending in the front-rear direction or the up-down direction substantially orthogonal to the lateral direction of the instrument panel core 10. As shown in FIG. 3 showing a 3-3 cross section, the ridge 16 has an outer shape of a substantially semicircular cross section, and a cavity 17 communicating with the cavity 15 in the rib 14 is formed therein. Has been done. In addition, one end of the ridge 16 continues to the runner portion 12.

In the instrument panel core 10 having the above structure, the rib 14 has a high load resistance, and in particular, load deformation or pressure deformation in the central portion is prevented. In addition, the ribs 14 and the ridges 16 that are thicker than other normal thickness portions have the hollow portions 15 and 17 inside, so that the increase in thickness is small and the difference in shrinkage due to the partial difference in thickness is small. As a result, the surface of the instrument panel core 10 is less likely to be deformed. Also, the rib 1
4 and the ridges 16 have the hollow portions 15 and 17
Due to the presence of, the increase in weight of the instrument panel core 10 is suppressed. The instrument panel core is covered with a skin such as a resin or a fabric at a part or front of the surface thereof through a cushioning material such as urethane foam, and is finally used as a vehicle instrument panel.

Next, a method of molding the instrument panel core will be described. The mold 20 shown in FIG. 4 is used for molding an instrument pamel core, and is a mold for injection molding. The mold 20 has a split mold structure including a convex mold 22 having a convex mold surface and a concave mold 24 having a concave mold surface, and has a cavity 25 formed therein.
A gate 26, a runner 27, which leads to the cavity 25,
The sprue 28 is formed. In the figure, 29 is a sprue bush.

The cavity surface 30 of the convex mold 22 forms the back surface of the instrument panel core, and the cavity surface 31 of the concave mold 24 forms the front surface of the instrument panel core. As shown in FIG. 5 showing a mold section corresponding to the 2-2 section of the instrument panel core 10, the convex cavity surface 30 has a rib shape having a substantially triangular cross section at the position where the rib 14 is formed. A recessed channel 33 is formed. It is preferable that the triangular sectional shape of the flow path 33 does not form an undercut shape. Further, as shown in FIG. 6 showing a mold section corresponding to the section 3-3, a groove 34 having a substantially semicircular section is formed at a position where the protrusion 16 is formed. The flow path 33 is formed laterally with respect to the instrument panel core 10, and the groove 3
4 is formed in the front-back direction or the up-down direction. The groove 34
And the flow path 33 communicate with each other and to the gate 26 and the runner 27.

In the mold 20, a convex mold 22 is mounted as a movable mold and a concave mold 24 is mounted as a fixed mold in an injection molding device (not shown), and a nozzle 36 of an injection cylinder is connected to the concave mold 24. A gas inflow pipe 38 is provided in the nozzle 36, and a high pressure gas or a foaming gas can be injected into the mold 20 from the tip of the nozzle via the gas inflow pipe 38. The gas inflow pipe 38 is connected to a gas supply device such as a gas cylinder (not shown). In addition,
This nozzle 36 is known as a nozzle for gas injection. Then, the instrument panel core is molded as follows.

First, the mold 20 is clamped, the molten thermoplastic resin is injected from the nozzle 36 of the injection cylinder, and the cavity 25 is almost completely filled. At this time, the groove 34
The flow path 33 is also filled with the molten thermoplastic resin 40 as shown in FIGS. 7 and 8.

Immediately after that, high-pressure nitrogen gas is injected into the mold 20 from the nozzle 36 through the gas inflow pipe 38. The injected gas passes through the runner 27 and the gate 26, and pushes the molten thermoplastic resin in the cavity 25 while pressing it. At that time, the flow path 33 passes through the portion where the gas easily advances, that is, the groove 34 where the cavity surface spacing is large.
Reach the department. As a result, as shown in FIG. 9 and FIG.
In the portion and the flow path 33, the gas presses the molten thermoplastic resin 40 against the inner wall surface (cavity surface) to form hollow portions 17 and 15 in the center of the inside. Further, in the other portions of the cavity 25, no cavity is formed by the gas in the molten thermoplastic resin, and there is no fear that the strength of the instrument panel core obtained will decrease. The pressure of the nitrogen gas varies depending on the type of thermoplastic resin used, the size and shape of the instrument panel core, the position and number of ribs, etc., but is a polypropylene resin with filler (PPF resin).
As an example of the case of using 10 to 30 MPa.

After the molten thermoplastic resin is cured, the mold 2
The instrument panel core 10 shown in FIG. 1 is obtained by opening 0, taking out the molded product, and cutting it off from the gate portion. In the obtained instrument panel core 10, the molten thermoplastic resin filling the flow path 33 of the mold serves as the ribs 14, and the molten thermoplastic resin filling the groove 34 serves as the ridges 16. In addition, since the ribs 14 and the ridges 16 are not undercut when the mold is removed, the ribs and the like are not damaged.

In the above-mentioned embodiment, the example in which the gas is injected using the nozzle has been shown, but the gas inlet directly communicating with the flow path 33 or the groove 34 is formed at a position different from the nozzle. May be. Further, the groove 34 may be rib-shaped.

[0021]

As shown and described above, in the instrument panel core of the present invention, since the rib provided on the back surface has a hollow portion inside, the rib portion is extremely thicker than other portions. In addition, it is possible to prevent the deformation caused by the difference in shrinkage due to the change in thickness. Moreover, it is possible to prevent the entire instrument core from becoming heavy due to the presence of the hollow portion despite having the rib.

Further, according to the molding method of the present invention, an instrument panel core having a reinforcing rib and having less shrinkage deformation can be easily molded by using conventional injection molding while preventing an undercut shape. There are advantages.

[Brief description of drawings]

FIG. 1 is a perspective view of an instrument panel core according to an embodiment of the present invention.

2 is a sectional view taken along line 2-2 of FIG.

3 is a sectional view taken along line 3-3 of FIG.

FIG. 4 is a sectional view corresponding to a section 4-4 in FIG. 1 regarding an embodiment of a mold used in the molding method of the present invention.

5 is an enlarged cross-sectional view of the mold corresponding to the 2-2 cross section in FIG. 1. FIG.

FIG. 6 is an enlarged sectional view of the die corresponding to section 3-3 in FIG. 1.

FIG. 7 is an enlarged cross-sectional view showing the vicinity of a die groove portion at the time of injection.

FIG. 8 is an enlarged cross-sectional view showing the vicinity of the mold flow path portion at the time of injection.

FIG. 9 is an enlarged cross-sectional view showing the vicinity of a die groove portion at the time of gas injection.

FIG. 10 is an enlarged cross-sectional view showing the vicinity of a mold flow path portion at the time of gas injection.

FIG. 11 is a cross-sectional view of a mold used for conventional molding.

FIG. 12 is a cross-sectional view of another mold used for conventional molding.

[Explanation of symbols]

 10 Instrument Panel Core 14 Rib 15 Cavity 20 Mold 25 Cavity 30 Cavity Surface 33 Flow Path 40 Molten Thermoplastic Resin

Claims (2)

[Claims] 1. A vehicle instrument panel core made of resin having a reinforcing rib on the back surface, wherein the rib is
An instrument panel core for a vehicle, which has a hollow portion inside. 2. A method for injecting a molten thermoplastic resin into a cavity of a mold to injection-mold an instrument panel core for a vehicle having a reinforcing rib on the back surface, wherein a cavity surface of a portion where the reinforcing rib is formed. Forming a flow path depressed in a rib shape having a substantially triangular cross section, and after injecting the molten thermoplastic resin, injecting a high-pressure gas or a foaming gas into the flow path in the cavity to remove the molten thermoplastic resin in the flow path. A method for molding a vehicle instrument panel core, comprising forming a reinforcing rib having a hollow portion inside by pressing against a wall surface of a flow path.