JP3600191B2 - In-mold insert for blow molding - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an insert in a blow molding die, which is arranged in a blow molding die during blow molding and a part of which is embedded in a blow molded product.
[0002]
[Prior art]
When a blow molded body such as an automobile spoiler is mounted on a vehicle body or the like, a part of a fixture is fixed to the blow molded body at the time of blow molding, as disclosed in Japanese Patent Application Laid-Open No. 10-235721, for example. A method of attaching a blow molded body to a vehicle body or the like by using a method is generally performed.
As an example of such a fixture (hereinafter referred to as an insert), an insert 1 of the type shown in FIG. 4 is known. The insert 1 includes a first flange portion 3 embedded in plastic at one end of a shaft portion 2 and a second flange portion 4 having a larger area at a position spaced apart from the first flange portion 3 of the shaft portion 2 by a predetermined distance. In addition, the other end side of the shaft portion 2 with respect to the second flange portion 4 is a fixed portion (a cracked clip pin) 5.
[0003]
When the insert 1 is embedded in the plastic of the blow-molded body, the insert 1 is inserted into the blow-molding mold according to a conventional method, and the second flange portion 4 is inserted into the blow-molding mold so as to face the cavity. The first flange portion 2 is protruded into the cavity along the wall surface. Subsequently, the molten parison is extruded between a pair of open blow molding dies, both dies are closed and sandwiched, and high-pressure air is blown into the parison to perform blow molding. As a result, the parison expands in the cavity and is blow-molded into a shape along the inner wall surface of the mold to form a required plastic molded body (blow molded body), and the insert 1 is embedded in the blow molded body.
FIG. 5 shows the insert 1 inserted into the blow mold 6 and embedded in the plastic of the blow molding 7.
[0004]
In the process of blow molding, the plastic comes into contact with and adheres to the upper surfaces of the first flange portion 3 and the second flange portion 4 of the insert 1, and then the gap between the first flange portion 3 and the second flange portion 4 is inserted into the shaft portion 2. , And the first flange portion 3 is involved. If the blow-molded plastic and the insert 1 are plastics that are weldable to each other, welding occurs at the close contact portion. Then, when the blow molding is completed and the blow molded body 7 is removed from the blow molding die 6, the blow molded body 7 to which the insert 1 is fixed can be obtained.
[0005]
[Problems to be solved by the invention]
By the way, when the plastic swells toward the shaft 2 between the first flange 3 and the second flange 4, the plastic swells to the first flange 3, the second flange 4, the shaft 2, and there. A ring-shaped enclosed space surrounded by incoming plastic is created, and the enclosed space becomes narrower as the plastic expands, so that the air trapped in the enclosed space is compressed to a high pressure. Therefore, the plastic cannot swell sufficiently, the gap 8 can be formed without sufficiently filling the first flange portion 3, the second flange portion 4, and the shaft portion 2, and the entrainment of the plastic becomes insufficient. Accordingly, the force for fixing the insert 1 is reduced.
[0006]
Furthermore, if the blow pressure inside the blow molded body is released and released to the atmosphere before the plastic is sufficiently solidified, the high-pressure air remaining in the gap 8 pushes the gap 8 apart, as shown by a virtual line in FIG. In some cases, a part of the plastic may bulge inward like a bump. Accordingly, the plastic that has been welded is peeled off from the insert 1 and the force for fixing the insert 1 is reduced. The fact that the temperature of the air in the gap 8 becomes high in a state close to adiabatic compression and the temperature of the plastic tends to be delayed at that portion is also a cause of such a tendency.
[0007]
The present invention has been made in view of the above problems of the related art, and has as its object to increase the fixing force of a plastic insert.
[0008]
[Means for Solving the Problems]
The present invention provides a blow molding in-mold insert comprising: a first flange portion embedded in plastic at one end of a shaft portion; and a second flange portion at a predetermined distance from the first flange portion of the shaft portion. On the side of the second flange portion facing the first flange portion, a ridge or a concave groove extending from the vicinity of the shaft portion to the outer periphery is formed. It is desirable that the ridges or grooves reach the shaft .
The blow mold inner insert is, for example, a fixture for fixing the blow molded body to another member, and is characterized in that a fixed portion is formed on the other end side of the shaft portion from the second flange. . This fixing part is, for example, a clip pin, but other forms of fixing part are also conceivable.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the insert in a mold for blow molding according to the present invention will be specifically described with reference to FIGS.
The insert 11 shown in FIG. 1 has the same basic structure as the insert 1 shown in FIG. 4, and includes a first flange portion 13 embedded in plastic at one end of a shaft portion 12 and the first flange portion 13 of the shaft portion 12. A second flange portion 14 having a larger area than the second flange portion 14 is provided at a position separated from the second flange portion 14 by a predetermined distance. The first and second flange portions 13 and 14 are formed substantially perpendicular to the shaft portion 12.
However, in the insert 11, on the side of the second flange portion 14 facing the first flange portion 13 (the surface facing the cavity side), a ridge 16 reaching the outer periphery of the second flange portion 14 from the shaft portion 12 is radiated. The insert 1 is different from the insert 1 shown in FIG. As shown in the enlarged view (d) of FIG. 1, the ridge 16 has undercut portions 16a formed on both sides.
[0010]
When the same blow molding as that of FIG. 5 is performed using the insert 11, as shown in FIG. 2, the plastic bulges out the gap between the first flange portion 13 and the second flange portion 14 toward the shaft portion 12. Meanwhile, air escapes from the ring-shaped space surrounded by the first flange portion 13, the second flange portion 14, the shaft portion 12, and the plastic bulging therethrough through the gap between the ridge 16 and the plastic. The plastic swells sufficiently to fill the space. As a result, the plastic is sufficiently entangled and the force for fixing the insert 11 is increased. In addition, it is possible to prevent the gap 8 from being pushed and bulged in the conventional insert 1.
[0011]
FIG. 3A illustrates the state of this air escape. In the process of bulging, there is a gap between the plastic and the ridge 16 that are in close contact with the upper surface 14a of the second flange 14 and the upper surface 16b of the ridge 16. A gap 17 is formed through which air escapes from the space. The undercut portion 16a is for ensuring a sufficient air passage in the process of bulging, but this is not essential. Further, even if the gap 17 may be completely filled with plastic finally or during the blow molding, air escapes from the gap 17 until then. The air that has escaped to the outer periphery of the second flange 14 is discharged to the outside through the blow mold 6.
In addition, the same effect can be obtained by using the concave groove 18 as shown in FIG. Also in this case, the undercut portion 18a is not essential.
[0012]
In the above example, the fixing portion 15 is formed on the other end side of the shaft portion 12 from the second flange 14, but the insert in the mold for blow molding according to the present invention is not limited to such a fixing device. For example, the present invention may be applied to a hollow nozzle or the like, or to other uses.
[0013]
【The invention's effect】
By using the insert in the mold for blow molding according to the present invention, it is possible to increase the bonding force between the plastic and the insert of the blow molded article, and that the plastic is peeled off from the insert when the blow pressure is released. Can also be prevented.
[Brief description of the drawings]
FIG. 1 is a front view (a), a side view (b), a plan view (c), and a partially enlarged view (d) of a blow molding insert according to the present invention.
FIG. 2 is a sectional view illustrating a state at the time of the blow molding.
FIG. 3 is a cross-sectional view illustrating the operation of a ridge and a groove formed on a second flange portion of the blow molding insert according to the present invention.
FIG. 4 is a front view (a), a side view (b), and a plan view (c) of a conventional blow molding insert.
FIG. 5 is a cross-sectional view illustrating a state during the blow molding.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 Insert 12 Shaft part 13 1st flange part 14 2nd flange part 15 Fixed part 16 Convex ridge 17 Gap 18 Groove

Claims (3)

A first flange portion embedded in plastic at one end of the shaft portion; and a blow molding inner insert having a second flange portion at a position spaced from the first flange portion of the shaft portion by a predetermined distance, wherein the second flange portion is provided. A ridge or a concave groove extending from the vicinity of the shaft portion to the outer periphery on the side facing the first flange portion. The inner mold insert for blow molding according to claim 1, wherein the ridge or the groove reaches a shaft portion. The blower according to claim 1 or 2, which is a fixture for fixing the blow molded body to another member, wherein a fixed portion is formed on the other end side of the shaft portion with respect to the second flange. In-mold insert for molding.

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