JP2009023186A - Mold for blow molding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold for blow molding which achieves a large reduction in the resistance of the blow air passage in addition to securing excellent mold temperature controllability and preventability of product shape deformation. <P>SOLUTION: The mold for blow molding is composed of a core mold which has an air blow-out hole for blow molding and is positioned on the inner circumferential side of a parison having a fixing part on the smaller diameter side and a fixing part on the larger diameter side and a blow mold for blow molding the parison into a final product shape between it and the core mold. The air blow-out hole is opened to the outer circumferential surface of the core mold on the edge of the smaller diameter side in stead of the fixing part on the smaller diameter side. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a blow mold.
In addition, the present invention relates to a blow mold that achieves good blowability in blow molding.

  Conventionally, a boot for a constant velocity joint made of a thermoplastic elastomer material is a parison formed by injection-molding a parison having a large-diameter side attachment portion, a small-diameter side attachment portion, and a hollow blow portion corresponding to the bellows portion, and after cooling. Is taken out together with the core mold of the injection mold, mounted on the blow mold, and the bellows part is molded by blowing air from the core mold into the blow part.

However, in this type of molding method, the core mold at the time of injection molding is used as it is as a support for supporting the inner peripheral side of the parison during blow molding, and in that case, gas is injected into the core mold. It is necessary to incorporate a mechanism for this, and the structure of the core type becomes complicated.
Therefore, it is desirable to use a separate member from the core mold at the time of injection molding as the support at the time of blow molding. In that case, it is possible to prevent the gas injected inside the parison from leaking to the outside. However, it is important to accurately blow-mold the bellows.

In particular, in the triport type joint boot, since the large-diameter side attachment portion has an irregular shape in the circumferential direction, it is difficult to prevent gas leakage at the large-diameter side attachment portion.
Furthermore, a certain clearance is unavoidable between the blow mold and the large-diameter fixed part of the parison to prevent biting of the mold, preventing the gas injected inside the parison from leaking outside. It was difficult to do.

This point will be described with reference to FIGS.
FIG. 3 is a partially enlarged view showing gas leakage at the time of blow molding in FIG.
This type of blow molding mold includes a first core mold 200 positioned on the inner peripheral surface side of the large diameter side mounting portion 100 and a second core mold positioned on the inner peripheral surface side of the small diameter side mounting portion 300. The core mold 500 is divided into 400 and includes an air outlet 700 for blow molding, and the blow mold 600 that blow-molds the parison 160 into the final product shape between the core mold 500. Yes.
And if gas is injected from the air jet nozzle 700, as shown in FIG. 3, the large diameter attaching part 100 will move to the blow die 600 side (radially outward).

As a result, as indicated by the arrows, the gas leaks outside the mold through a gap formed between the inner peripheral surface of the large-diameter mounting portion 100 and the outer peripheral surface of the first core mold 200.
For this reason, this kind of conventional technology has caused a problem that the bellows portion cannot be blow-molded with high accuracy.

As an improved mold, a mode has been proposed in which an uneven portion is provided at a location where the axial end of the large-diameter side mounting portion and the end surface of the core mold are in contact with each other (Japanese Utility Model Publication No. 4-73527, No. 2007-15149).
However, since the concavo-convex portion is formed at the axial end of the large-diameter side mounting portion parallel to the direction in which the gas injection pressure is applied, the concavo-convex engagement is released by the injection pressure or the concavo-convex portion is booted. Had caused problems to be damaged.

In addition, there was a problem that it was difficult to process the uneven portion into a mold.
Furthermore, there has been proposed a method in which the core mold is divided at each mountain portion and blow air is supplied from the respective divided gaps. However, the mold structure becomes complicated and causes a problem that the cost increases. In order to avoid deformation, the gap between the divided portions cannot be made larger than 0.1 mm. Therefore, it was impossible to avoid a decrease in blowability due to an increase in blow air circuit resistance.

Japanese Utility Model Publication No. 4-73527 JP 2007-15149 A

  The present invention has been made in view of the above-mentioned problems, and the main technical problem is that the blow air circuit resistance is greatly improved while ensuring good mold temperature control and product deformation prevention. An object of the present invention is to provide a blow mold that can achieve a significant reduction.

  Blow molding mold for boots of the present invention is located on the inner peripheral surface side of a parison having a small diameter side mounting portion and a large diameter side mounting portion, and a core mold having an air outlet for blow molding, In the blow molding die comprising a blow die for blow-molding the parison into a final product shape with the core die, the air blower outlet is located on the small-diameter end portion side of the core die. It is characterized by opening in the outer peripheral surface of the mold.

  According to the blow molding die of the first aspect of the invention, the blow air circuit resistance can be greatly reduced while ensuring the product deformation prevention.

Moreover, according to the blow molding die of the invention described in claim 2, it is possible to improve the blow molding performance while ensuring the prevention of product deformation.
Furthermore, according to the blow molding die of the invention described in claim 3, the optimum blow molding performance can be exhibited while ensuring the product deformation prevention.

  Furthermore, according to the blow mold of the invention of claim 4, good mold temperature controllability can be secured.

Hereinafter, a blow molding die according to the present invention will be described with reference to the drawings.
FIG. 1 is a sectional view of a blow molding die according to the present invention.

  That is, the blow molding die according to the present invention is located on the inner peripheral surface side of the parison 16 including the small-diameter side attachment portion 3 and the large-diameter side attachment portion 1 and includes an air outlet 7 for blow molding. It is comprised from the core metal mold | die 5 and the blow metal mold | die 6 which blow-molds the parison 16 in the final product shape between this core metal mold | die 5. FIG.

The core mold 5 includes an inner mold 51 and an outer mold 52 surrounding the inner mold 51.
In this blow molding die, the air outlet 7 has an end portion with a smaller diameter than the small-diameter side attachment portion 3 via an air ejection path 4 formed by a gap between the inner die 51 and the outer die 52. It opens to the outer peripheral surface of the core mold 5 on the side.
More specifically, the air outlet 7 is a mode in which the air outlet 7 is provided at a position close to the small-diameter side mounting portion 3 in the small-diameter side burr portion 8 of the parison 16.

Moreover, it is preferable that the clearance gap of an air blower outlet (7) is 0.1-1 mm.
Furthermore, since the temperature control circuit 2 of the core mold 5 is provided in each of the inner mold 51 and the outer mold 52, the temperature of the mold can be adjusted with high accuracy.
In particular, since the plurality of temperature control circuits 2 are provided at positions closer to the parison 16 of the outer mold 52, the temperature of the mold can be adjusted with higher accuracy.

  The present invention is not limited to the best mode for carrying out the invention described above, and various other configurations can be adopted without departing from the gist of the present invention.

It is sectional drawing of the blow molding die which concerns on this invention. It is sectional drawing of the blow molding die concerning a prior art. It is the elements on larger scale which showed the leak of the gas at the time of the blow molding of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Large diameter side attaching part 2 Temperature control circuit 3 Small diameter side attaching part 4 Air ejection path 5 Core mold 6 Blow mold 7 Air outlet 8 Small diameter side burr part 16 Parison 51 Inner mold 52 Outer mold

Claims (4)

  A core mold having an air outlet (7) for blow molding, located on the inner peripheral surface side of a parison (16) having a small diameter side mounting portion (3) and a large diameter side mounting portion (1) 5) and a blow mold (6) for blow molding the parison (16) into a final product shape between the core mold (5) and the air outlet (7) Is opened on the outer peripheral surface of the core mold (5) on the small diameter end side with respect to the small diameter side attaching part (3).   The said air blower outlet (7) is the small diameter side burr | flash part (8) of the said parison (16), Comprising: It provided in the position close | similar to the said small diameter side attaching part (3). Blow molding mold.   The blow mold according to claim 1 or 2, wherein a gap between the air outlets (7) is 0.1 to 1 mm.   The blow molding die according to any one of claims 1 to 3, wherein the temperature control circuit (2) of the core die (5) is provided outside the air ejection path (4). Type.

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