JP3757935B2 - Foam molding insert and foam molding product manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of manufacturing an integrally molded product in which an insert and a foamed layer are laminated by foam molding, and to an insert used for the manufacturing method.
[0002]
[Prior art]
For example, an automobile instrument panel is made up of a hard resin base, a soft resin skin, and a foam layer formed between the base and the skin. First, the substrate is molded by injection molding or the like, and the skin is molded by powder slush molding or vacuum molding. Then, the skin is placed on the lower mold surface of the foam mold, the base is placed on the upper mold surface, and a predetermined amount of foamed resin is injected into the cavity formed between the skin and the base. By performing foam molding, a foam layer integrally joined to the substrate and the skin is formed.
[0003]
In general urethane foam molding, there is an open injection method in which a predetermined amount of foamed resin is injected into the lower mold while the upper mold and the lower mold are opened, and then the mold is closed to perform foam molding. However, in order to shorten the molding cycle, it is necessary to shorten the reaction time of urethane, and in the open injection method, there is a problem that it is necessary to take care of the work from injection to mold closing.
[0004]
In recent years, therefore, a closed injection method in which a foamed resin is injected after the mold is closed has been adopted. In the case of closed injection, a foamed resin having a high reaction rate can be used, and the time required for foam molding can be shortened, so that productivity is improved. In this closed injection method, an injection hole communicating with the cavity is formed in the upper mold and the base, and the foamed resin is injected from the injection hole after the upper mold and the lower mold are closed.
[0005]
An instrument panel or the like has a complicated shape, and the cross-sectional area of the cavity forming the foamed layer is not uniform. Therefore, when molding by the open injection method, while moving the nozzle along the lower mold, a large amount of foamed resin is injected into a portion where the cavity volume is large, and a small amount of foam resin is injected into a portion where the volume is small. In this way, the foamed resin layer is devised so that the foamed layer to be molded has an optimal shape by preventing insufficient filling and overfilling of the foamed resin.
[0006]
However, in the case of the closed injection method, it is impossible to inject while moving the nozzle. Therefore, one or a plurality of injection holes are formed at a place considered to be optimal for the mold and the substrate, and the inside of the cavity is formed from the injection holes. Foamed resin is injected. However, if the position and the number of the injection holes are inappropriate, a portion where the foamed layer is not formed is generated, or the foaming pressure is too high, and the skin after demolding is swollen. In such a case, it is necessary to adjust the position and number of injection holes, but then the foaming mold and the injection hole of the base must also be changed, and the mold for molding the base needs to be modified. Also occurs.
[0007]
Further, it may be difficult to form the injection hole at an appropriate position, and it may take time for the injection due to the plurality of injection holes, or a problem may occur at a site where the foamed resin intersects.
[0008]
Also, if there are narrow parts or protrusions in the cross section of the cavity as in the instrument panel, the flow of the foamed resin is obstructed at that part. There was a problem that the defect was further promoted.
[0009]
Japanese Patent Application Laid-Open No. 09-262849 describes a method of forming a foam layer by a closed injection method using a substrate having injection holes formed with a plurality of slits extending radially from the center. In this way, by making the interval or length of the slits nonuniform, it is possible to distribute the injection amount of the foamed resin, and to prevent insufficient filling or overfilling of the foamed resin.
[0010]
[Patent Document 1]
JP 09-262849 [0011]
[Problems to be solved by the invention]
However, in the method of forming a plurality of slits extending radially from the center, it is necessary to include a portion including the injection hole and the entire slit in the nozzle hole area of the injection nozzle, compared to the case where the entire injection hole is a through hole. The area of the penetrating part is small. Therefore, there is a problem that the foaming cell is easily broken because the resistance during injection is large and the injection pressure is also required to be high. Further, if the tip end face of the injection nozzle and the substrate are not in close contact with each other, there is also a problem that the foamed resin leaks from between them.
[0012]
Furthermore, although the amount of foamed resin injected can be allocated in the direction in which the slit extends, the motion vector of the allocated foamed resin is always in the downward direction, so it is injected from the slit and collides with the lower mold. The direction of the motion vector of the foamed resin was indefinite, and it was difficult to cause the foamed resin to flow in the desired direction.
[0013]
The present invention has been made in view of such circumstances, and by distributing the foamed resin injected from the injection hole in a small amount in a certain direction, the foamed resin is insufficiently filled or overfilled. The purpose is to prevent. Another object of the present invention is to further prevent insufficient filling or overfilling of the foamed resin by imparting a motion vector in a predetermined direction to the foamed resin injected into the cavity.
[0014]
[Means for Solving the Problems]
A feature of the foam molding insert of the present invention that solves the above problems is an insert in which a foam layer is integrally formed on the back surface of the foam molding die, and the base and the foam resin are injected through the base. And a distribution means that projects to the back side of the substrate and divides the injection hole into a plurality of injection paths . The distribution means is a plate-like rib, and the injection hole has a different opening area depending on the distribution means. That is, it is divided into a plurality of injection paths .
[0015]
Distribution means, the plate-like ribs. The distribution means preferably has an inclined surface that is inclined with respect to the injection direction of the foamed resin into the injection hole. Furthermore, it is desirable that the distribution means is integrally formed with the base body when the base body is formed.
[0016]
In addition, the foam molding product of the present invention is characterized in that the foam molding insert of the present invention is arranged so that the surface is along one mold surface of the foam molding die, and between the back surface of the insert and the other mold surface. A method of manufacturing a foam molded article by closed injection that forms a foam layer integrally joined to the back surface by injecting foam resin into the cavity formed in the mold and foam-molding, and injected from the injection hole. The foamed resin is distributed in a plurality of directions in the cavity by the distributing means.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
The foam molding insert of the present invention has a distribution means that projects to the back side of the substrate and partitions the injection hole into a plurality of injection paths, and the injection hole is partitioned into a plurality of injection paths by the distribution means. The foamed resin injected into the injection hole is injected into the cavity from a plurality of injection paths, but a large amount of foamed resin is injected from the injection path with a large opening area, and a small amount of foam is injected from the injection path with a small opening area. Resin will be injected. Therefore, an injection path with a large opening area is formed on the cavity side where a large amount of foamed resin is required, and an injection path with a small opening area is formed on the cavity side where only a small amount of foaming resin is required. It is possible to appropriately distribute without bias, and it is possible to prevent insufficient filling or overfilling of the foamed resin.
[0018]
Further, since the distributing means is present in the injection hole, if the plate-shaped rib is used , the increase in resistance during injection is slight, and the injection pressure does not further increase. Therefore, there is no problem that the foam cell is broken.
[0019]
The insert of the present invention can be formed from a resin, an iron plate or the like using a molding method such as injection molding or press molding.
[0020]
The distribution means divides the injection hole into a plurality of injection paths, and is a plate-like rib formed across the injection hole . Or it is good also as a structure which comprised the injection hole from the some pipe. By making the opening areas of the plurality of injection paths different, the foamed resin can be distributed in an amount corresponding to each opening area. This distribution means can be formed separately from the base body and can be integrated with the base body by adhesion or welding, but it is desirable that the distribution means be integrally formed with the base body when the base body is formed. As a result, the number of steps for forming the distribution means and the number of steps for bonding to the substrate can be reduced, and the cost can be further reduced.
[0021]
The distribution means preferably has an inclined surface that is inclined with respect to the injection direction of the foamed resin into the injection hole. By doing so, the foamed resin distributed to the plurality of injection paths is directed in the inclination direction of the inclined surface and injected into the cavity, and flows in the cavity with a motion vector directed in a predetermined direction. Accordingly, a large amount of the foamed resin can be flowed in a desired direction and can be more reliably distributed, so that insufficient filling and overfilling of the foamed resin can be further reliably prevented.
[0022]
It is desirable that the inclined surface of the distribution means be inclined to the injection path side having a large opening area among the plurality of injection paths partitioned by the distribution means. As a result, since a large amount of foamed resin can be caused to flow with a motion vector to a cavity that requires a large amount of foamed resin, the foamed resin can be caused to flow almost simultaneously throughout the cavity, and the time can be shortened. Therefore, a sound foam layer can be formed in a short time, and productivity is improved.
[0023]
Note that the number of distributing means may be one or plural. The height at which the dispensing means protrudes from the back surface of the substrate into the cavity increases as the distribution efficiency increases. However, if the dispensing means extends to the vicinity of the mold surface facing the substrate, the feel of the molded product deteriorates or the foamed resin It may interfere with flow. Therefore, it is preferable to make the protrusion height as high as possible within a range in which the distance between the tip of the distribution means and the opposite mold surface is about 3 to 5 mm.
[0024]
In the method for producing a foamed molded product of the present invention, the foamed layer is molded by closed injection. In closed injection, a density gradient occurs due to the part of the foamed resin, and there is a part where the foam layer is not formed. The swelling of the skin is likely to occur. However, by using the insert of the present invention, the foamed resin can be properly distributed, and the foaming pressure becomes uniform over almost the entire cavity, so that such a problem can be prevented in advance.
[0025]
【Example】
Hereinafter, the present invention will be described specifically by way of examples. In this embodiment, the present invention is applied to the manufacture of an instrument panel for an automobile.
[0026]
Example 1
FIG. 1 is a perspective view of a main part viewed from the surface side of the insert of this embodiment, and FIG. 2 is a sectional view thereof. The insert includes a base 1 made of a hard resin, an injection hole 10 through which the foamed resin is injected through the base 1, a first injection path 11 and a second injection path that protrude to the back side of the base 1 and pass through the injection hole 10. And plate-like ribs 13 divided into twelve.
[0027]
The substrate 1 is formed by injection molding, and the ribs 13 are integrally formed at the same time as the substrate 1 is molded. The rib 13 crosses the injection hole 10 to divide the injection hole 10 into two first injection paths 11 and a second injection path 12, and the opening area of the second injection path 12 is the first injection path 11. Has been bigger. The rib 13 protrudes at a height of H = 4 mm on the back side of the substrate 1 and the surface on the injection channel 12 side is a plane inclined by θ = 30 ° toward the injection channel 12 with respect to the axial center of the injection hole 10. ing.
[0028]
In the instrument panel manufacturing method of this embodiment using this insert, as shown in FIG. 3, a soft resin skin 2 formed in advance by powder slush molding, vacuum molding or the like and shaped into a predetermined shape is used. The movable mold 4 is closed with the fixed mold 3 in a state where the movable mold 4 is disposed on the mold surface of the fixed mold 3 and the insert 1 is disposed on the mold surface of the movable mold 4. The movable mold 4 is formed with a nozzle hole 40 communicating with the injection hole 10 of the insert 1. A cavity is formed between the back surface of the insert 1 and the skin 2. The cavity 50 on the first injection path 11 side has a small volume, and the cavity 51 on the second injection path 12 side has a large volume and the distance to the cavity end is long.
[0029]
Next, the injection nozzle 6 is inserted into the nozzle hole 40, and the injection nozzle 6 is inserted into the injection hole 10 of the insert 1. The tip of the injection nozzle 5 comes into contact with the insert 1. When a predetermined amount of foamed resin is closed and injected from the injection nozzle 6 in this state, the foamed resin is injected into a plurality of first injection paths 11 and second injection paths 12 by ribs 13 as shown in FIG. A small amount of foamed resin is distributed in the first injection path 11, and a large amount of foamed resin is distributed in the second injection path 12.
[0030]
In the first injection path 11, the motion vector of the foamed resin is injected in substantially the same direction as the axial center of the injection hole 10, and the motion vector after collision with the skin 2 is indefinite. On the other hand, since the foamed resin injected from the second injection path 12 is injected while being guided by the inclined surface 14 of the rib 13, a large amount of motion vector in a predetermined direction is provided in the cavity 51 in the direction of the arrow after collision with the skin 2. To flow.
[0031]
After foaming of the foamed resin was completed, the movable mold 4 and the stationary mold 3 were opened, and the molded product was removed. As a result, no abnormalities such as sink marks or blisters were found on the surface of the skin 2, and the design was good. .
[0032]
In the present embodiment, the inclined plate-like rib 13 formed integrally with the base body is used at the time of forming the base body. However, as shown in FIG. As shown in FIG. 5, a rib 13 having a triangular cross-section with two inclined surfaces may be joined later, depending on the case.
[0033]
(Example 2)
The principal part perspective view which looked at the insert 1 of the 2nd Example from the surface side in FIG. 6 is shown. In this insert 1, in addition to the first rib 13 similar to that in the first embodiment, a second rib 15 extending in a direction perpendicular to the rib 13 is formed, and the second injection path 12 referred to in the first embodiment is Further divided into a third injection path 16 and a fourth injection path 17.
[0034]
If such an insert 1 is used, the injection hole 10 is divided into three injection paths, and the first rib 13 is inclined toward the third injection path 16 and the fourth injection path 17 side. The flow can be further controlled. Therefore, even when the cavity has a more complicated shape, insufficient filling or overfilling of the foamed resin can be prevented.
[0035]
Example 3
FIG. 7 shows a cross-sectional view of the main part of the insert 1 of the third embodiment. The insert 1 has the same configuration as that of the first embodiment except that the rib 13 is not inclined and is parallel to the central axis of the injection hole 10.
[0036]
If such an insert 1 is used, it is difficult to give a motion vector in a predetermined direction to the foamed resin flowing in the cavity, but the ribs are different depending on the opening area difference between the first injection path 11 and the second injection path 12. The amount of the foamed resin injected into both sides of the 13 can be properly distributed.
[0037]
【The invention's effect】
That is, according to the insert and the method for producing a foam molded product of the present invention, insufficient filling and overfilling of the foamed resin can be reliably prevented, so that the defective rate in foam molding can be greatly reduced. Since the defective rate of the foam molded product can be reduced simply by forming the distribution means in the insert, there is no need to modify the foam mold.
[Brief description of the drawings]
FIG. 1 is a perspective view of an essential part of an insert according to an embodiment of the present invention as viewed from the surface side.
FIG. 2 is a cross-sectional view of an essential part of an insert according to an embodiment of the present invention.
FIG. 3 is an explanatory view showing a state in which an insert according to an embodiment of the present invention is placed in a foam mold and foam-molded by a closed injection method.
4 is a cross-sectional view of a principal part showing another aspect of the insert of Example 1. FIG.
5 is a cross-sectional view of a principal part showing another aspect of the insert of Example 1. FIG.
FIG. 6 is a perspective view of an essential part of an insert according to a second embodiment of the present invention as viewed from the surface side.
FIG. 7 is a sectional view of an essential part of an insert according to a third embodiment of the present invention.
[Explanation of symbols]
1: Insert 2: Skin 3: Fixed type 4: Movable type 6: Injection nozzle 10: Injection hole
11: First injection path 12: Second injection path 13: Rib (distribution means)
14: Inclined surface 50, 51: Cavity

Claims (4)

An insert in which a foam layer is integrally formed on the back surface, disposed in a foam mold,
A base, an injection hole through which the foamed resin is injected, and a distribution means that projects to the back side of the base and divides the injection hole into a plurality of injection paths ,
The foam molding insert, wherein the distribution means is a plate-like rib, and the injection hole is divided into a plurality of injection paths having different opening areas by the distribution means . An insert in which a foam layer is integrally formed on the back surface, disposed in a foam mold,
  A base, an injection hole through which the foamed resin is injected, and a distribution means that projects to the back side of the base and divides the injection hole into a plurality of injection paths,
  The foam molding insert characterized in that the distribution means has an inclined surface inclined with respect to the injection direction of the foamed resin into the injection hole. The foam molding insert according to claim 1 or 2 , wherein the distribution means is integrally formed with the base when the base is molded. The insert according to any one of claims 1 to 3 is disposed so that a surface thereof is along one mold surface of a foaming mold, and the cavity is formed between a back surface of the insert and the other mold surface. A method for producing a foam-molded article by closed injection that forms a foam layer integrally bonded to the back surface by injecting a foam resin from an injection hole and foam-molding,
A method for producing a foam molded article, wherein the foamed resin injected from the injection hole is distributed by the distributing means in a plurality of directions in the cavity.

Images