JPH06305006A - Blow molding machine - Google Patents

Abstract

PURPOSE:To prevent a preform from being interposed between a lip mold and a temperature regulating pot by centering the preform. CONSTITUTION:A temperature regulating pot 20 has a temperature regulating cavity 22 formed at an inner center and a temperature regulating water channel 26 provided around the cavity 22, thereby regulating a temperature of a preform 300 by inserting the preform 30 into the cavity 22, and has a centering core 30 for centering the preform 300 by inserting the core 30 into the preform 300.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a blow molding machine,
In particular, it relates to a blow molding machine for centering a preform to be inserted into a temperature control pot.

[0002]

2. Description of the Related Art Conventionally, a so-called four-station molding machine is known as a blow molding machine which is called a hot parison system or a one-stage system and which performs stretch blow molding while retaining a heat quantity at the time of injection molding of a preform. There is.

A four-station molding machine injects molten resin into an injection cavity, cools it to form a preform, then adjusts the temperature of this preform, and then blow-molds in a blow cavity mold. Then, the final container is taken out by an ejector.

In this blow molding machine, the step of adjusting the temperature of the preform aims at providing the preform with a temperature distribution in the longitudinal direction. As a temperature adjusting device for performing such temperature adjustment, for example, JP-A-63-207
There is one disclosed in Japanese Patent No. 630.

In this temperature control device, the preform held in the lip shape is housed in the cavity of the temperature control pot consisting of the temperature control block. Then, air is pre-blown by pressurizing air into the preform through an air blowing passage provided inside the rod inserted in the center of the lip type,
By this preliminary blow, the temperature of the preform is controlled by bringing the preform into overall contact with the cavity surface of the temperature control pot.

[0006]

However, in the above conventional temperature control device, when the preform is bent when the preform is stored in the cavity of the temperature control pot, if the preform is bent, the outer diameter of the preform and the temperature control pot inlet. Since the inner diameters are almost the same, the preform was sometimes sandwiched between the lip mold and the temperature control pot. Even if the preform is not sandwiched, if the preform is bent and pre-blow is performed at a position where the axis of the preform deviates from the center of the cavity of the temperature control pot, the preform blows from the outer wall of the preform to the cavity surface. Since the distance to reach the preform differs depending on the axial position of the preform, it cannot be drawn into a preform with a uniform wall thickness, and the heat capacity differs due to the difference in wall thickness, and temperature control cannot be performed as planned. It was

In some cases, preliminary blow is not performed,
In this case, the temperature of the preform is adjusted by radiant heat from the outside. In this case, if the preform is bent, the distance from the heat radiation surface to the outer wall of the preform differs depending on the axial position of the preform, and the amount of heat supplied that is inversely proportional to the square of this distance becomes different, as planned. It becomes impossible to control the temperature.

Bending of these preforms occurs when the preform has a partial temperature deviation and the degree of contraction changes depending on the site, and in particular, it tends to occur as the temperature of the preform increases. Further, when the preform is conveyed from the injection molding process to the temperature control process, a force may be applied to the preform due to the moment of inertia to deform the preform.

Alternatively, according to a preform molded from a material having a large shrinkage rate such as polypropylene, not only the temperature tends to be unbalanced but it is easily bent, but also the large shrinkage rate shortens the length in the axial direction. The bottom of the preform did not come into contact with the cavity surface at the bottom of the temperature control pot, and the temperature could not be controlled sufficiently. According to the above conventional device,
Although the preform is brought into contact with the cavity surface by preliminary blowing, even if air is introduced into the preform, there is a drawback in that it is difficult to perform centering because the air does not have directionality.

The present invention has been made to eliminate the drawbacks of the prior art, and its purpose is to prevent or prevent the preform from being sandwiched between the lip mold and the temperature control pot. In addition to the purpose, it is an object of the present invention to provide a blow molding machine in which the bottom of a preform can be surely brought into contact with the cavity surface of the bottom of the temperature control pot.

[0011]

In order to achieve the above object, a blow molding machine according to a first aspect of the present invention has a bottomed cylindrical preform molded by injection or extrusion, and has a heat amount at the time of molding. In a molding machine having a temperature control station for controlling the temperature before blow molding in the above state, the temperature control station includes a temperature control pot arranged around the preform, and the temperature control station inserted inside the preform. A centering core type that contacts the inner wall of the bottom of the reform and centers the preform.

A blow molding machine according to a second aspect is the blow molding machine according to the first aspect, wherein the temperature control pot has a temperature control cavity surrounding a side wall and a bottom wall of the preform, and the centering core mold is The bottom part of the preform is pushed down in the axial direction to be brought into contact with the bottom surface of the temperature control cavity.

Further, the blow molding machine according to claim 3 is
In claim 1 or claim 2, the centering core type has a temperature adjusting means by radiant heat in a region facing a side wall of the preform.

The blow molding machine according to claim 4 is
In Claim 3, the centering core type front end is insulated from the temperature adjusting means.

[0015]

In the blow molding machine according to the first aspect of the present invention, the centering core mold is inserted into the inside of the preform so that the centering of the preform can be performed by contacting the inner wall of the bottom. The bending of the preform can be corrected when inserting the preform into the cavity of the temperature control pot. Therefore, it is possible to prevent mold clamping failure such as the preform being sandwiched between the lip mold and the temperature control pot.

Further, in the blow molding machine according to the second aspect, since the bottom portion of the preform is pushed down in the axial direction by the centering core mold, the centering can be surely performed. Become.

Further, in the blow molding machine according to the third aspect, since the centering core mold has the temperature control means in the region facing the side wall of the preform, the temperature control means heats the preform. By this, a temperature distribution in the vertical direction can be provided even from the inside of the preform.

Further, in the blow molding machine according to the fourth aspect, since the tip end of the centering core type is insulated from the temperature adjusting means, the bottom part of the preform corresponding thereto is separated from the body part thereof. Well maintained at low temperatures. Therefore, when the preform is stretched by the centering core type, it is possible to relatively increase the stretching resistance of the bottom portion of the preform to which a large force is easily applied, so that it is possible to prevent the tip portion from becoming thin.

[0019]

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

FIG. 1 shows a blow molding machine 200 according to an embodiment.
FIG. In the figure, a blow molding machine 20
A turntable 220 is provided on the machine base 210 of No. 0, and the turntable 220 can be intermittently rotated with respect to the machine base 210 in the direction of the arrow in the figure. Then, the preform 3 injection molded at the injection molding station 202
00 is rotated by a turntable 220 to execute a temperature control process of a preform, a temperature control station 204,
It goes through each station of a stretch blow station 206 that executes a biaxial stretch blow step of the preform and an eject station 208 that executes a step of taking out a molded product.

Here, an enlarged sectional view of the mold structure of the temperature control station 204 is shown in FIG. This mold structure includes a lip mold 10, a temperature control pot 20, and a centering core 30.

The lip mold 10 has a pair of split molds 10a and 10a which can be opened in the left-right direction in the drawing, and
The preform 30 has the lip cavity surface 12 that defines the outer wall of the lip portion 300 a of the preform 300.
Holds 0. A guide hole 32 is formed in the center of the lip mold 10 so that the centering core 30 can be inserted therethrough.
The centering core 30 can be inserted from above the lip mold 10 into the held preform 300. In addition, the guide hole 32 has a tapered surface that widens upward in order to facilitate the insertion of the centering core 30. The temperature control pot 20 has a temperature control cavity 22 formed therein, and the preform 300 is controlled by the temperature control cavity 22. It is designed to be housed in the cavity 22. The temperature control pot 20 is configured by stacking ring-shaped temperature control blocks 24 that are divided into four stages in the vertical axis direction, and each temperature control block 24 stores hot water or the like controlled to a predetermined temperature. A water channel 26 for circulating the temperature control medium is provided. In addition, changing to this waterway 26,
An electric resistance heating type heater can also be adopted.

The centering core 30 has a hollow cylindrical shaft portion 34.
And a core pin 40 inserted in the center thereof. The lower end of the shaft portion 34, as a seal portion 36, is in close contact with the inner wall of the lip portion 300a of the preform 300.
An air blowing passage 38 is formed in a ring shape between the inner wall of the shaft portion 34 and the outer wall of the core pin 40. The air blowing passage 38 blows air into the preform 300 to perform a preliminary blow, and the preblowing can bring the preform 300 into contact with the temperature control cavity surface 28 as shown in FIG. it can.

The core pin 40 is located in the center axis of the temperature control cavity 22 so that the core pin 40 can be inserted into the preform 300 to center the preform 300. Moreover, the core pin 40 is inserted into the preform 300 to extend the preform 300 in the axial direction, and is driven so that the bottom portion 300b thereof is brought into contact with the bottom portion 28a of the temperature control cavity surface 28. Therefore, the bottom portion 300b of the preform 300 can be surely brought into contact with the temperature control cavity surface 28 to enable sufficient temperature control. In particular, the preform 300 made of polypropylene or the like having a large shrinkage ratio is shortened in the axial direction by shrinking, and the bottom portion 300b is hard to come into contact with the temperature control cavity surface 28, so that it is stretched in the axial direction by the core pin 40. It is effective to do. Further, since the core pin 40 has the heating means, for example, the heater 42 therein, the preform 300 can be heated from the inner wall side thereof to adjust the temperature, and thus the preform 300 can be easily stretched. There is.

Further, the tip portion 40a of the core pin 40 is
It is formed of a resin such as nylon or a heat insulating material such as Teflon, and it is difficult for the heat of the heater 42 to be transferred. Therefore, the bottom portion 300b of the preform 300 corresponding to the tip end portion 40a of the core pin 40 is heated at a relatively low temperature, and is difficult to be stretched. Alternatively, instead of this, a heat insulating material may be formed between the tip portion 40a and the heater 42.

A heating piece 44 is attached to the end portion of the core pin 40, and the neck portion 30 of the preform 300 is attached.
By heating 0c to make it easier to stretch the lower neck portion 300c, it is possible to prevent the shoulder portion of the final container corresponding to the lower neck portion 300c from becoming thick after blow molding. As the heating piece 44, one made of a material having a high thermal conductivity such as aluminum or one coated with far-infrared ray is used.

This embodiment is constructed as described above,
The operation will be described below.

As shown in FIG. 1, the preform 300 is held by the lip mold 10 and conveyed to the temperature control station 204. During this conveyance, the preform 30 is conveyed.
A bend may occur at 0. Alternatively, the preform 300 may be bent due to uneven temperature during injection molding.

Therefore, in order to correct this bending, FIG.
A centering core 30 is used as shown in FIG. That is, the centering core 30 is moved downward from above the lip die 10 and inserted into the guide hole 32, and the downward movement is continued as it is so that the tip 40a of the core pin 40 is moved to the preform 30.
The bottom part 300b of 0 is reached. At this time, core pin 4
Since 0 is located on the central axis of the temperature control cavity 22,
By contacting the tip of the core pin 40 with the bottom of the preform 300, the bent preform 300 can be positioned on the central axis of the temperature control cavity 22 and straightened to perform centering.

Then, when the preform 300 is conveyed from the injection molding station 202 to the temperature control station 204, the preform 300 is stretched by the contracted length.

The preform 300 has a core pin 4
Since it is heated by the heater 42 provided inside 0, it is easily stretched. However, preform 3
Since the bottom portion 300b of No. 00 is heated to a relatively low temperature by the tip portion 40a of the core pin 40 and is difficult to be stretched, the bottom portion 300b does not become thin even if a large force is applied.

After or after the operation of the centering core 30 is completed, the temperature control pot 20 is moved upward to house the preform 300 in the temperature control cavity 22. At this time, since the preform 300 is straightened, a part of the preform 300 may hit the opening 20a of the temperature control pot 20, or the temperature control pot 20 may be damaged.
The preform 300 is not sandwiched between the lip mold 10 and the lip mold 10.

FIG. 2 shows the state in which the preform 300 is housed in the temperature control cavity 22 in the shape of good quality. In the figure, the bottom portion 300 of the preform 300
Since b is in contact with the bottom portion 28a of the temperature control cavity surface 28, sufficient temperature control is possible at this portion.

After the centering and stretching of the preform 300 are completed, or at the same time as the centering and stretching, the preform 300 is pre-blown.

Here, the lip portion 1 of the preform 300
At 0, since the gap is closed by the seal portion 36, preliminary blow can be sufficiently performed. Then, pre-blowing is performed, and the preform 300 contacts the temperature control cavity surface 28 as shown in FIG. In this way, the preform 300 is brought into contact with the temperature control cavity surface 28 not only in the body portion 300d but also in the bottom portion 300b, and a sufficient temperature control is performed as a whole.

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

For example, the above-mentioned embodiment is a temperature control device for performing preliminary blow, but the present invention is not limited to this, and a temperature control device for performing temperature control by radiant heat without performing preliminary blow may be used. .

[0038]

As described above, in the blow molding machine according to the first aspect, since the preform can be centered and the bending of the preform can be corrected, the preform has a lip type and a temperature control pot. It is possible to prevent a mold clamping defect such as being sandwiched between and.

Further, in the blow molding machine according to the second aspect, the bottom portion of the preform can be pushed down in the axial direction to surely perform the centering.

Further, in the blow molding machine according to the third aspect, since the preform can be warmed by the centering core type temperature controlling means, the temperature of the preform can be appropriately controlled.

In the blow molding machine according to the fourth aspect, since the tip of the temperature control core mold is insulated from the temperature control means, it is possible to prevent the bottom of the preform from becoming thin.

[Brief description of drawings]

FIG. 1 is a plan view showing a blow molding machine 200 according to an embodiment.

FIG. 2 is a vertical cross-sectional view showing a mold structure of a temperature control station including a lip mold, a temperature control pot, and a centering core.

FIG. 3 is a vertical cross-sectional view showing a state after pre-blowing the preform in the mold structure of FIG.

[Explanation of Codes] 10 Lip Type 20 Temperature Control Pot 22 Temperature Control Cavity 26 Water Channel 30 Centering Core 40 Core Pin 42 Heater

Claims (4)

[Claims] 1. A molding machine having a temperature control station for controlling the temperature of a bottomed tubular preform molded by injection or extrusion before blow molding while retaining the heat amount at the time of molding. The conditioning station is a temperature control pot that is arranged around the preform, a centering core type that is inserted inside the preform and contacts the bottom inner wall of the preform to center the preform, A blow molding machine characterized by having. 2. The temperature control pot according to claim 1, wherein the temperature control pot has a temperature control cavity surrounding a side wall and a bottom wall of the preform, and the centering core mold pushes down a bottom part of the preform in an axial direction. A blow molding machine, wherein the blow molding machine is brought into contact with the bottom surface of the temperature control cavity. 3. The blow molding machine according to claim 1 or 2, wherein the centering core mold has a temperature control means by radiant heat in a region facing the side wall of the preform. 4. The blow molding machine according to claim 3, wherein a tip end portion of the centering core die is insulated from the temperature adjusting means.