JPH0422986Y2 - - Google Patents

Description

[Detailed Description of the Invention] <<Industrial Application Field>> The present invention relates to an apparatus for cooling a molded product from the inside by injecting liquefied gas such as liquefied carbon dioxide into a synthetic resin blow molding apparatus.

<<Prior Art>> Generally, in a blow molding apparatus, a molded product is cooled from the outside by circulating a coolant such as cooling water within a mold. For this reason, since the molded product is cooled on one side, the cooling rate is slow, and the mold occupancy time becomes long, resulting in low production efficiency.

Therefore, there are methods in which a liquid cooling medium is forced into the hollow body formed in the mold to cool the molded product from the inside (for example, Japanese Patent Application Laid-open No. 7867/1983),
By supplying low-temperature liquefied gas to the mold, the preform is expansion-molded and cooled from the inside (for example, JP-A No. 51-52467).
is proposed.

[Problem to be solved] In the conventional internal cooling method, when injecting a cooling medium into a molded product, the cooling medium injection pipe is arranged concentrically inside the compressed air blowing pipe, and the cooling medium is injected into the molded product. The nozzle body will be screwed onto the tip of the injection tube,
Since the external dimensions at the attachment point between the nozzle body and the coolant injection pipe are larger than the external dimensions of the coolant injection pipe and the nozzle body, the flow of compressed air for expanding the balisong is disturbed, which affects the quality of the molded product. will be given. Furthermore, in blow molding, the wall thickness of the part along the split surface of the mold becomes thicker, and depending on the shape of the mold, there may be a difference in the amount of elongation during expansion. Furthermore, differences in the distance from the coolant passage in the mold to the mold surface cause cooling differences in the molded product, and conventional cooling devices supply the cooling medium so that it acts evenly around the entire circumference of the molded product. As a result, there is a problem that differences in cooling rate occur in each part of the molded product, causing distortion and stress in the product.

[Problems to be solved] The present invention provides a cooling device that can uniformly cool the entire molded product. In a cooling device for a blow molding machine in which pipes are arranged concentrically through the blow molding machine to cool the blow molded product from the inside, a spherical nozzle body is installed at the tip of the cooling liquefied gas injection pipe so that at least its lower half is blown into the cooling device. It is characterized in that it is formed so as to protrude from the tip of the nozzle tube, and that a liquefied gas outlet is opened in the spherical part of the spherical nozzle body.

<Operation> In the present invention, a spherical nozzle body is attached to the tip of the cooling liquefied gas injection tube which is arranged concentrically through the blowing tube of the blow molding machine, and at least the lower half of the spherical nozzle body protrudes from the tip of the blowing nozzle tube. This structure prevents the nozzle body from disturbing the flow of compressed air for balisong expansion flowing through the blowing pipe, and the liquefied gas outlet is opened in the spherical part of the spherical nozzle body, which prevents liquefaction. It becomes possible to set the gas ejection direction over a wide range according to the shape of the molded product.

《Example》 Fig. 1 shows a schematic configuration diagram of a cooling device in a blow molding machine. The gas injection pipe 4 is connected to the compressed air blowing pipe 3.
A nozzle body 5 is screwed onto the tip of the cooling liquefied gas injection pipe 4.

As shown in FIGS. 2 and 3, the nozzle body 5 is formed into a spherical shape, and a liquefied gas outlet 7 is opened in the shape of a slit on the circumferential surface of the spherical portion. The nozzle body 5 is attached to the tip of the cooling liquefied gas injection tube 4 with its tip half protruding from the end of the blow tube 3 on the mold cavity side. Therefore, the liquefied gas is ejected from the nozzle body 5 in a fan shape.

In the figure, reference numeral 8 denotes a liquefied carbon dioxide gas storage tank, and 9 denotes a liquefied carbon dioxide gas supply pump, which are configured so that the liquefied carbon dioxide gas is supplied into the mold in a liquid state.

FIG. 4 shows a modification of the spherical nozzle body 5, in which a plurality of liquefied gas jet ports 7 each consisting of a small diameter hole are opened in a row in the spherical portion of the nozzle body 5.

The liquefied gas outlet 7 is formed in accordance with the shape of the molded product so as to eject the liquefied gas toward locations where cooling delays are likely to occur (for example, locations where the wall thickness is large).

In the cooling device for a blow molding machine having the above-described configuration, the spherical nozzle body 5 is disposed such that at least half of its tip protrudes beyond the tip of the blowing pipe 3. Even if the nozzle part 5 is disposed penetratingly inside the blowing pipe 3, the resistance to the flow of the blowing compressed air is small, and the flow of the blowing compressed air is made uniform without being disturbed, and the flow inside the balisong is reduced. to inflate the balisong uniformly.

In addition, the liquefied gas is ejected in a liquefied state from the spherical cooling liquefied gas ejection nozzle 5, and the molded product is powerfully cooled by the heat of vaporization during sublimation and the cold heat possessed by the liquefied gas. In this case, since the nozzle body 5 is spherical, the liquefied gas can also be ejected diagonally upward, so that the entire molded product can be cooled to an even degree.

《Effects》 The present invention has a cooling liquefied gas injection tube that is placed concentrically through the blow molding machine.
Since the spherical nozzle body is formed so that at least its lower half protrudes from the tip of the blowing nozzle pipe, the nozzle body can be prevented from disturbing the flow of compressed air for balisong expansion flowing inside the blowing pipe. In addition to being able to form the product uniformly, the liquefied gas jetting port is opened in the spherical part of the spherical nozzle body, so the liquefied gas jetting direction can be set over a wide range to match the shape of the molded product. It becomes possible,
The degree of cooling in each part of the molded product can be made uniform. This not only eliminates distortion in the molded product, but also prevents the generation of internal stress and increases the strength of the product.

Furthermore, since the cooling liquefied gas jetting nozzle is formed into a spherical shape, the cooling liquefied gas jetting port can be opened in any direction, and the cooling liquefied gas can be spouted according to the shape of the molded product. You can easily do that.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of a cooling device in a blow molding machine, Figure 2 is a longitudinal cross-sectional view of a cooling liquefied gas jet nozzle, Figure 3 is a perspective view of the nozzle in Figure 2, and Figure 4 is a modification of the nozzle. FIG. 3... Blowing pipe, 4... Liquefied gas injection pipe for cooling, 5... Spherical nozzle body, 7... Liquefied gas spout.

Claims (1)

[Scope of Claim for Utility Model Registration] 1. In a cooling device for a blow molding machine, in which a cooling liquefied gas injection pipe is disposed concentrically through the blow pipe of the blow molding machine to cool the blow molded product from the inside. , A spherical nozzle body is formed at the tip of the cooling liquefied gas injection pipe in a state in which at least a half of the tip side thereof protrudes from the tip of the blowing nozzle pipe, and a liquefied gas jetting port is opened in the spherical part of the spherical nozzle body. A liquefied gas injection cooling device for a blow molding machine. 2. The liquefied gas injection cooling device for a blow molding machine as claimed in claim 1, wherein the liquefied gas outlet is formed in the shape of a slit in the spherical part of the spherical nozzle body. 3. The liquefied gas injection cooling device for a blow molding machine according to claim 1, wherein liquefied gas ejection ports each having small holes are arranged in a row on the spherical surface of a spherical nozzle body.