JP2008254364A - Blow molding die - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a blow molding die which can inhibit a gas leakage during blow molding and blow mold a bellows with high precision. <P>SOLUTION: This blow molding die is divided into a first core mold positioned on the inner peripheral surface side of a large dia. side mounting part, and a second core mold positioned on the inner peripheral surface side of a small dia. side mounting part. In addition, the blow molding die is configured of a core mold with an air jet nozzle for blow molding and a blow mold which blow molds a parison into an end-product shape between this blow mold and the former core mold. Besides, the blow molding die features an annular groove formed in the side surface of the first core mold so as to receive the end part, in the axial direction, of the large dia. side mounting part. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a blow mold.
The present invention also relates to a blow mold that prevents the gas injected inside the parison from leaking outside during 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.
In addition, a certain clearance is unavoidably present between the blow mold and the large-diameter fixed part of the parison to prevent mold biting, 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. 6 is a partially enlarged view showing gas leakage at the time of blow molding in FIG.
This kind of blow molding mold includes a first core mold 200 located 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 and the core mold 500. Yes.
Then, when gas is injected from the air outlet 700, the large-diameter mounting portion 100 moves to the blow mold 600 side (radially outward) as shown in FIG.
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 type 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 boot is formed by the concavo-convex portion. Had caused problems to be damaged.
In addition, there was a problem that it was difficult to process the uneven portion into a mold.

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 thereof is a blow capable of accurately performing blow molding of the bellows portion while suppressing gas leakage during blow molding. It is to provide a molding die.

  The blow molding mold for boots of the present invention includes a first core mold positioned on the inner peripheral surface side of the large diameter side mounting portion and a second core mold positioned on the inner peripheral surface side of the small diameter side mounting portion. In a blow mold comprising a core mold having an air outlet for blow molding, and a blow mold for blow molding a parison into a final product shape between the core mold, An annular groove for receiving the axial end of the large-diameter side attachment portion is formed on a side surface of the first core mold.

  According to the blow molding die of the first aspect of the invention, the bellows portion can be blow molded with high accuracy.

Moreover, according to the blow molding die of invention of Claim 2, the leakage of the gas injected at the time of blow molding can be prevented reliably.
Furthermore, according to the blow mold of the invention described in claim 3, the releasability of the product improves.

Furthermore, according to the blow molding die of the invention described in claim 4, it is possible to effectively prevent galling of the die.
Furthermore, according to the blow molding die of the invention described in claim 5, the inner peripheral surface of the large-diameter side mounting portion of the boot is not damaged at the time of mold release.

Furthermore, according to the blow molding die of the invention described in claim 6, it is possible to effectively prevent damage to the inner peripheral surface of the large-diameter side mounting portion of the boot at the time of mold release.
Furthermore, according to the blow molding die of the invention described in claim 7, the bellows portion can be blow-molded with high precision, particularly in a deformed boot.
Furthermore, according to the blow molding die of the invention described in claim 8, blow molding can be performed optimally.

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, and FIG. 2 is a partially enlarged view of FIG.
3 and 4 are partial sectional views showing other embodiments of the present invention.

  That is, the blow molding die according to the present invention includes a first core mold 2 positioned on the inner peripheral surface side of the large diameter side mounting portion 1 and a second core positioned on the inner peripheral surface side of the small diameter side mounting portion 3. The core mold 5 which is divided into the core mold 4 and provided with an air outlet 7 for blow molding, and the blow mold for blow molding the parison 16 into the final product shape between the core mold 5 6.

An annular groove 9 that receives the axial end 8 of the large-diameter side attachment portion 1 is formed on the side surface 12 of the first core mold 2.
The annular groove 9 has a shape that accepts the entire portion of the boot end 8 extending to the band mounting groove 10, that is, the side surface 12 on the large diameter side of the first core mold 2, and the band mounting groove 10. It is preferable in terms of sealing performance that the side surface 17 of the end portion 8 side is made flush with the outer peripheral surface of the end portion 8 and the inner peripheral surface 11 of the annular groove 9.
If the annular groove 9 is made deeper than this, the end 8 is undercut at the time of product release, making product release difficult.

In such a structure, when gas is injected from the air outlet 7, as shown by the arrow in FIG. 2, the gas acts to push the parison radially outward. And the inner peripheral surface 11 of the annular groove 9 are more firmly adhered to each other, so that no gas leaks to the outside.
Further, the inner peripheral surface 11 of the annular groove 9 is an inclined surface whose diameter increases toward the band mounting groove 10.
This facilitates mold release and does not damage the product during mold release.
Further, the side surface 12 of the first core mold 2 is an inclined surface in which a gap between the side surface 13 and the opposed side surface 13 of the blow mold 6 increases radially outward.
This effectively prevents the core mold 5 and the blow mold 6 from being galled.

Another embodiment of the present invention will be described with reference to FIGS.
In the embodiment of FIG. 3, chamfering is performed on the outer peripheral end portion 14 of the second core mold 4 where the first core mold 2 is in contact with the first core mold 2.
In order to efficiently adjust the temperature of the core mold 5, the joint portion between the first core mold 2 and the second core mold 4 is as close to the large-diameter side mounting portion 1 as possible. It is preferable.
However, in this case, the problem that the product is damaged by the outer peripheral end portion 14 of the second core mold 4 at the time of mold release is caused, but this problem can be effectively avoided by chamfering.

The embodiment of FIG. 4 is also for solving the problem that the product is damaged by the outer peripheral end 14 of the second core mold 4 at the time of mold release.
In other words, the position of the divided portion 15 in contact with the first core mold 2 of the second core mold 4 is provided at a position where the diameter is smaller than the inner diameter of the large-diameter mounting portion 1.
Thus, it is possible to avoid damaging the product by the outer peripheral end 14 of the second core mold 4 at the time of mold release.
This type of blow mold is particularly effective for the tripod type for constant velocity joints.
In addition, a thermoplastic elastomer material such as a polyester-based thermoplastic elastomer is suitably used as a boot molding material.

  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 the elements on larger scale of FIG. It is the fragmentary sectional view which showed the other Example of this invention. It is the fragmentary sectional view which showed the further another Example of 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 1st core metal mold | die 3 Small diameter side attaching part 4 2nd core metal mold | die 5 Core metal mold | die 6 Blow metal mold | die 7 Air outlet 8 End part 9 Annular groove 10 Band attachment groove | channel 11 Inside Peripheral surface 12 Side surface 13 Side surface 14 Outer peripheral edge

Claims (8)

  The first core mold (2) located on the inner peripheral surface side of the large diameter side mounting portion (1) and the second core mold (4) positioned on the inner peripheral surface side of the small diameter side mounting portion (3) The parison (16) is blow-molded into a final product shape between the core mold (5) having an air outlet (7) for blow molding and the core mold (5). In the blow molding die comprising the blow die (6), the axial end (8) of the large-diameter side attachment portion (1) is received on the side surface (12) of the first core die (2). A blow molding die for a boot, wherein an annular groove (9) is formed.   The blow mold according to claim 1, characterized in that the annular groove (9) has a shape for receiving the whole of the axial end (8) up to the band mounting groove (10).   The blow molding die according to claim 1 or 2, wherein the inner peripheral surface (11) of the annular groove (9) is an inclined surface whose diameter increases toward the band mounting groove (10). .   The side surface (12) of the first core mold (2) is an inclined surface in which a gap between the blow mold (6) and the opposite side surface (13) is increased radially outward. The blow molding die according to any one of claims 1 to 3.   5. The outer peripheral end (14) of a portion of the second core mold (4) in contact with the first core mold (2) is chamfered. The blow mold according to item.   The position of the split part (15) in contact with the first core mold (2) of the second core mold (4) is provided at a position where the diameter is smaller than the inner diameter of the large diameter mounting part (1). The blow molding die according to any one of claims 1 to 4.   The blow-molding die according to any one of claims 1 to 6, wherein the boot is a triport type for a constant velocity joint.   The blow mold according to any one of claims 1 to 7, wherein the boot is a thermoplastic elastomer material.

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