JPH06278196A - Blow molding machine - Google Patents

Abstract

(57) [Abstract] [Purpose] A preform having a temperature distribution in the circumferential direction is obtained through an injection core mold having a cooling temperature distribution in the circumferential direction, and the difference in stretching resistance causes It is to provide a blow molding machine capable of adjusting the wall thickness distribution. An inner flow channel 44 and an outer inner flow channel 44 formed in the injection core type core pin 10 in the axial direction.
Flow path for communicating the inner flow path 44 and the outer flow path 46 on the tip side of the core pin 10 with the outer flow path 46 that occupies a region corresponding to the local cooling part of the preform that is a part of the outer circumference of the core pin 10 in the circumferential direction. The channels 42 are formed, and such a configuration allows local cooling.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a blow molding machine,
In particular, the present invention relates to a blow molding machine capable of adjusting the wall thickness distribution of the side wall of the final container.

[0002]

2. Description of the Related Art Conventionally, as a blow molding machine, which is called a hot parison method or a one-stage method, for stretch blow molding while retaining a heat quantity at the time of injection molding of a preform, a so-called 4-station molding apparatus and 3-station molding machine are used. A molding device is known.

A four-station molding apparatus injects molten resin into an injection cavity, cools it, molds a preform, and then adjusts the temperature of the preform to give a temperature distribution in the longitudinal direction, and then blows it. Blow molding is performed in the cavity mold, and the final container is taken out by an ejector.

The three-station molding apparatus cools the molten resin injected into the injection cavity to mold the preform, blows the preform in the blow cavity mold without adjusting the temperature, and finally The container is taken out by an ejector.

In these blow molding machines, the molten resin injected into the injection cavity is cooled by a cooling water passage provided inside the injection cavity mold and the injection core mold. As a document showing a cooling method using such a cooling water channel, for example, Japanese Patent Publication No. 63-41731.
The gazette is mentioned.

FIG. 8 shows an injection core type cooling water passage. The figure (A) is the longitudinal cross-sectional view, and the figure (B) is a cross-sectional view. In these drawings, a recess 102 is formed in the injection core mold 100 in the axial direction, and a cooling pipe 110 having an outer diameter smaller than the inner diameter of the recess 102 is inserted. In this way, the inner water passage 122 is formed inside the pipe of the cooling pipe 110, the outer water passage 124 is formed outside the pipe, and the molten resin is cooled by flowing cold water from the inner water passage 122 to the outer water passage 124 in the direction of the arrow in the figure. Then, the preform was formed.

According to such a cooling water passage of the injection core mold 100, since the outer water passage 124 is formed concentrically with the injection core mold 100, the cold water flows uniformly in the circumferential direction and the cooling water flow passage is even in the circumferential direction. The injection core mold 100 was cooled to the temperature of. The molten resin was cooled to a uniform temperature in the circumferential direction by the injection core mold 100 cooled to such a temperature, and a preform having a substantially uniform temperature in the circumferential direction was formed. Further, since the temperature is substantially uniform in each part in the circumferential direction, this preform can be uniformly drawn with substantially uniform drawing resistance in each part in the circumferential direction.

[0008]

By the way, there are various types of bottles for blowing and molding injection-molded preforms, and not only bottles having a circular cross section but also non-cross sections. Some are circular and some have handles.

Among these bottles, a bottle having a circular cross section has a uniform pre-form because the distance from the center of the blow core mold to the cavity surface of the blow cavity mold is uniform in the circumferential direction during blow molding. It may be blown uniformly in the radiation direction. Therefore, it suffices to uniformly cool the periphery of the molten resin, obtain a preform that has a substantially uniform temperature in the circumferential direction and can be uniformly stretched, and blow this.

However, when a bottle having a non-circular cross section or a bottle having a handle is blow-molded,
The distance from the center of the blow core mold to the cavity surface of the blow cavity mold varies depending on the circumferential portion. Therefore, when a preform that can be stretched substantially uniformly in the circumferential direction is blown, the portion of the preform having the short distance comes into contact with the inner surface of the cavity first to stop the stretching and becomes thick, and the portion of the preform having the long distance is blown. Is further stretched to be thin. As described above, there is a drawback that the thickness of the bottle varies depending on the part.

The present invention has been made in order to eliminate the drawbacks of this prior art, and its purpose is to cool the injected molten resin to different temperatures in the circumferential direction and to make the temperature distribution in the circumferential direction. Another object of the present invention is to provide a blow molding machine capable of adjusting the wall thickness distribution of the side wall of the final container by obtaining preforms having different stretching resistances depending on the parts.

[0012]

In order to achieve the above object, a blow molding machine according to a first aspect of the present invention blow-molds a preform molded by injection or extrusion in a state of retaining the heat quantity at the time of molding. In this molding apparatus, the molding apparatus injection-molds the preform using an injection core mold and an injection cavity mold, and the injection core mold has a cooling medium flow passage therein. Is a first flow path formed in the central portion of the injection core mold in the axial direction, and a second flow path formed in the axial direction outside the first flow path, A third flow path that allows the first flow path and the second flow path to communicate with each other on the tip side of the injection core mold, wherein the second flow path is the local cooling of the preform. A region corresponding to a part and a region corresponding to a part of the injection core mold in the circumferential direction. Characterized in that it comprises a local cooling flow path occupied.

Further, in the blow molding machine according to a second aspect, in addition to the structure of the first aspect, the second flow path is formed on the entire circumference of the injection core mold at a part in the axial direction of the injection core mold. It is characterized by having a flow channel occupying a corresponding region.

Further, the blow molding machine according to claim 3 is
In addition to the configuration of claim 1 or claim 2, the injection core mold includes a core pin having a hollow portion inside, and the hollow pin disposed in the hollow portion to connect the hollow portion to the first flow path and the second passage. A hollow pipe that is divided into a flow path, and the hollow pipe,
A groove for forming the local cooling flow path is provided in a part of the outer wall in the circumferential direction, and the outer wall without the groove is in close contact with the inner wall of the core pin.

[0015]

In the blow molding machine according to the first aspect, since the second flow passage is formed outside the first flow passage and in a partial region in the circumferential direction, the cooling temperature distribution is provided in the circumferential direction. It is possible to obtain an injection core mold that has.

According to the preform injection-molded by using such an injection core mold, it is possible to cool the molten resin at a low temperature in the region where the second flow path is formed and reduce the amount of heat retained, which is a countermeasure for this. The stretch resistance is increased in the preform portion. On the other hand, since the cooling temperature is relatively high in the region that does not have the second flow path, the amount of heat retained by the molten resin increases,
The stretch resistance of the corresponding portion of the preform becomes small. In this way, preforms having a temperature distribution in the circumferential direction and different stretching resistances can be obtained. Moreover,
Since the molten resin is cooled at different temperatures in the circumferential direction while being injected, the temperature distribution can be reliably provided in the circumferential direction in a short time even in a molding machine without a temperature control stage.

Therefore, a second flow path is formed in the region of the injection core mold corresponding to the portion of the preform where the stretch ratio should be increased to increase the stretch resistance of the preform, while the stretch ratio should be decreased. When this preform is blown by reducing the stretching resistance of the preform without forming a second flow path in the injection core type region corresponding to the portion of the preform, the stretching resistance is increased by the portion with a large stretching resistance. The part with a small diameter is pulled, and the wall thickness distribution on the peripheral surface of the final container can be adjusted.

In the blow molding machine according to claim 2,
In the partial area of the second flow path, the flow path occupies the entire circumference area of the injection core mold, so that the circumference of the preform can be uniformly cooled in this entire circumference area.
In this way, it is possible to obtain an injection core mold in which a region having a temperature distribution in the circumferential direction and a region having a uniform temperature in the circumferential direction are combined, and preforms having various temperature distributions are obtained to obtain various shapes. The thickness distribution of the final container with various shapes can be adjusted.

In the blow molding machine according to claim 3,
Since the first flow path and the second flow path are partitioned by the hollow pipe having the groove, the local cooling flow path can be formed with a simple configuration. Further, since the outer wall of the hollow pipe in which the groove is not formed is in close contact with the inner wall of the core pin, the area of the core pin corresponding to this is also necessary for the mold release of the preform by the first flow path inside the hollow pipe. Can be cooled to temperature.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a blow molding machine 2 according to the first embodiment.
It is a top view which shows 00. In the figure, a rotary plate 220 is provided on a machine base 210 of the blow molding machine 200, and the rotary disk 220 can be intermittently rotated with respect to the machine base 210 in the direction of the arrow in the figure. And
The preform 300 injection molded at the injection molding station 202 is rotated by the turntable 220,
Temperature control station 2 that executes the temperature control process of the preform
04, a stretch blow station 206 that executes a biaxial stretch blow step of the preform, and an eject station 208 that executes a take-out step of the molded product.

Here, an enlarged sectional view of the mold structure of the injection molding station 202 is shown in FIG. This mold structure includes an injection core mold 240, an injection cavity mold 260, and a lip mold 2.
And 80. In the figure, the lip die 280 has a pair of split dies 284 and 286 that can be opened in the left-right direction in the figure, and has a cavity surface 282 that defines the outer wall of the lip portion 310 of the preform 300. Is. In addition, the injection cavity mold 260 is
The preform 300 has a cavity surface 262 that defines the outer wall of the body portion 320, and a molten resin filling gate 264 is formed at the lower end portion. The injection cavity mold 260 has a cooling passage 266 formed therein, and is capable of molding the preform 300 by cooling the injected molten resin to a predetermined temperature. Further, the injection core mold 240 includes the base end portion 242 and the core pin 1.
The core pin 10 defines the inner wall of the preform 300.

3A and 3B are views showing the core pin 10. FIG. 3A is a longitudinal sectional view thereof, and FIG. 3B is a transverse sectional view thereof. The core pin 10 includes an outer layer portion 20 and a pipe portion 30.
It consists of and.

The outer layer portion 20 is, as shown in FIG.
It is a rod-shaped member having a rounded tip portion corresponding to the inner wall of the preform. Further, a concave portion 22 is formed in the central portion of the outer layer portion 20 in the axial direction.

The pipe portion 30 is a tubular member having an outer diameter substantially equal to the inner diameter of the recess 22 of the outer layer portion 20. Also,
An outer wall groove 32 that is continuous in the axial direction is formed on the outer wall of the pipe portion 30 (see FIG. 3B). The outer wall groove 32 is formed with a width that does not exceed a half circumference of the outer circumference of the pipe portion 30, so that when the outer wall groove 32 is inserted into the recess 22, the non-formed portion of the outer wall groove 32 can be closely fitted to the inner surface of the recess 22. Has become.

The pipe portion 30 is connected to the outer layer portion 20.
The lower end of the pipe portion 30 and the recess 22.
To form a space between the bottom of the
The pipe 34 of the pipe portion 30 is connected to, for example, a cooling water inlet (not shown) to form an inner flow path 44, and the outer wall groove 32 is connected to, for example, a cooling water outlet (not shown). Can be the outer flow path 46.

Thus, the inner channel 44, the communication channel 42,
And a cooling water channel that passes through the outer flow channel 46 is formed. Also,
Since the concave portion 22 and the pipe portion 30 can be fitted tightly to each other, a gap is not formed in another region, another water channel is not formed, and a cooling water channel is formed only in a desired region. You can However, even in the region where the outer flow path 46 is not provided, since the recess 22 and the pipe portion 30 are in a close-fitting state, the cold water flowing through the inner flow path 44 causes heat exchange with the outer layer portion 20 of the core pin 10. Therefore, the preform 300 can be cooled to a temperature at which it can be released from the mold.

Further, the heat exchange rate can be increased by forming the pipe portion 30 from a material having a high thermal conductivity such as copper or brass.

Next, regarding the region where the outer flow path 46 is to be formed in the core pin 10 and the stretching action of the preform, FIG.
It will be described based on. This figure is a view showing the stretch ratio of a preform (not shown) injection-molded around the core pin 10, and shows the final container 5 after being blown around the core pin 10.
0 is shown in phantom.

This preform is stretched in the left direction at a large stretch ratio and in the right direction at a small stretch ratio so that the final container 50 has an oval cross section. Therefore, it is desirable to reduce the stretching resistance of the right resin and increase the stretching resistance of the left resin so that the right resin is pulled in the left direction. For that purpose, it is necessary to increase the amount of heat held by the resin on the right side and decrease the amount of heat held by the resin on the left side.

Therefore, the outer flow path 46 of the core pin 10 is
By forming only on the left side in the figure, this core pin 1
0 has a cooling temperature distribution in which the temperature on the left side is low and the temperature on the right side is relatively high. Corresponding to the cooling temperature distribution of the core pin 10, a temperature distribution in which the temperature on the left side is low and the temperature on the right side is relatively high is also formed in the preform, and the stretching resistance on the left side is large and the stretching resistance on the right side is small. As a result, the resin on the right side is pulled by the resin on the left side, and the thickness distribution of the final container 50 can be adjusted.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 5 is a view showing a vertical cross section of the core pin 60 of the blow molding machine according to the second embodiment.
However, at the lower end of the core pin 60 in the axial direction, it is formed so as to occupy the entire peripheral region of the pipe portion 63. The other structure is similar to that of the first embodiment, and the description thereof is omitted.

The core pin 60 is shown in FIG.
As shown in (B), the thickness of the lower portion of the pipe portion 63 is uniform in the circumferential direction so that the outer flow passage 66 is formed concentrically with the pipe 64 of the pipe portion 63. Further, the BB cross section is as shown in FIG. 3B as in the first embodiment. Since the pipe portion 63 is formed in this manner, the outer flow passage 66 is formed over the entire circumference of the pipe portion 63 in the lower portion and a partial region in the circumferential direction of the pipe portion 63 in the upper portion. Is formed in.

Therefore, the temperature distribution of the core pin 60 is low throughout the circumference in the lower part, is low in the region where the outer flow passage 66 is formed in the upper part, and is relatively high in other regions. There is.

Then, a preform (not shown) having a temperature distribution corresponding to the cooling temperature distribution of the core pin 60 is obtained, and this is blow-molded. For example, the lower part has a circular cross section and the upper part has a non-cross section. Round final containers can be molded.

The present invention is not limited to the above embodiment, and various modifications can be made within the scope of the gist of the present invention.

For example, as shown in FIG. 6, the core pin 70
The outer wall groove 74 of the pipe portion 72 is formed at two opposite locations, and the preform is largely stretched in the left-right direction in the figure and slightly stretched in the up-down direction in the figure to obtain a final container having an oval cross section. It is also possible to mold 76.

Further, when the present invention is applied and the bottle and the handle member are integrated by insert blow molding, the region that engages with the handle member is locally cooled to have a thick wall, and the engagement strength is increased. It can also be increased.

Further, the temperature difference between the side having the outer flow path and the side not having the outer flow path in the core pin is too large, and when the preform is blow-molded, the thickness of the bottle corresponding to the side not having the outer flow path is It can be too thin.
In this case, as shown in FIG.
2, the outer peripheral surface of the pipe portion 82 and the inner peripheral surface of the outer layer portion 84 do not correspond to each other on the side where the outer flow path 86 is not provided (the right side in the figure), and a gap 88 is provided between them to cool the cooling water. The temperature difference can be adjusted by cooling so as to flow. Alternatively, as shown in FIG. 7 (B), in the core pin 90, the tube 94 of the pipe portion 92 is expanded into a long hole by expanding the hole toward the side not having the outer flow path 96 (right side in the figure). The temperature difference can be adjusted by increasing the cooling efficiency. Thus, FIG. 7 (A)
In each drawing of (B), the thickness of the right side portion of the bottle indicated by the chain double-dashed line can be adjusted.

[0040]

As described above, according to the blow molding machine of the first aspect, it is possible to form the temperature distribution in the circumferential direction of the preform by the injection core mold having the cooling temperature distribution in the circumferential direction. Further, there is an effect that the stretching resistance can be adjusted according to the difference in the stretch ratio of the preform, and the wall thickness distribution of the final container can be adjusted.

Further, according to the blow molding machine of the second aspect, the injection core mold in which the region having the temperature distribution in the circumferential direction and the region having the uniform temperature in the circumferential direction are combined is used, and the blow molding machine can perform the circumferential and axial directions. There is an effect that a preform having a temperature distribution can be obtained and the wall thickness distribution of final containers having various shapes can be adjusted.

Further, according to the blow molding machine of the third aspect, the first channel and the second channel can be formed with a simple structure, and the area of the core pin having no second channel is also the first. There is an effect that it can be cooled by the flow path.

[Brief description of drawings]

FIG. 1 is a plan view showing a blow molding machine according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing an injection molding station in the blow molding machine of FIG.

3A and 3B are views showing a core pin in the injection molding station of FIG. 2, in which FIG. 3A is a longitudinal sectional view thereof and FIG. 3B is a transverse sectional view thereof.

4 is a drawing showing the stretch ratio of the preform injection-molded around the core pin of FIG. 3, showing the final container after blowing around the core pin in phantom.

FIG. 5 is a vertical sectional view of a core pin of a blow molding machine according to a second embodiment of the present invention.

FIG. 6 is a diagram showing a stretch ratio of preforms in other examples.

FIG. 7 is a diagram showing means for adjusting the temperature difference of the core pin in another embodiment.

8A and 8B are diagrams showing a core pin in a conventional injection molding station, FIG. 8A being a longitudinal sectional view thereof, and FIG. 8B being a transverse sectional view thereof.

[Explanation of symbols]

 10 core pin 20 outer layer part 22 concave part 30 pipe part 32 outer wall groove 34 pipe 42 communication flow path 44 inner flow path 46 outer flow path

Claims (3)

[Claims] 1. A molding apparatus for blow molding a preform molded by injection or extrusion in a state of retaining the amount of heat at the time of molding, which molding apparatus uses an injection core mold and an injection cavity mold. The preform is injection-molded, the injection core mold has a cooling medium flow passage therein, and the cooling medium flow passage is formed in a central portion of the injection core mold in the axial direction over a first direction. A flow channel, a second flow channel formed outside the first flow channel in the axial direction, the first flow channel and the second flow channel, the tip side of the injection core mold And a third flow path communicating with each other, wherein the second flow path is a region corresponding to the local cooling portion of the preform and corresponds to a part of the injection core mold in the circumferential direction. A blow molding machine comprising a local cooling flow path occupying a region to be blown. 2. The first flow path according to claim 1, wherein the second flow path has a flow path that occupies a region corresponding to the entire circumference of the injection core mold in a part of the injection core mold in the axial direction. Blow molding machine. 3. The injection core mold according to claim 1, wherein the injection core mold includes a core pin having a hollow portion inside,
A hollow pipe that is disposed in the hollow portion and divides the hollow portion into the first flow path and the second flow path, and the hollow pipe is a partial region in a circumferential direction of an outer wall thereof. A blow molding machine having a groove for forming the channel for local cooling, and an outer wall not having the groove is in close contact with an inner wall of the core pin.