JPH0286424A - Molding method for deformed hollow container - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for stretch blow molding an injection molded thermoplastic synthetic resin parison into a deformed hollow container.

[Prior Art] Packaging containers made of thermoplastic resin such as polyethylene terephthalate are formed by stretching an injection-molded parison with a bottom in the axial direction and blowing air into the parison.

[Problems to be Solved by the Invention] Typically, a parison is injection molded using a cavity mold and a core mold inserted into the center of the cavity, and the core mold is extracted from the parison after molding.

In consideration of this extraction after molding, the circumferential side of the core mold is inclined inward from the mouth molding part of the parison to the tip where the inner bottom end of the parison is molded. Even if the parison is attached to the core mold, the core mold can be easily extracted.

For this reason, the shape of a parison formed by injection molding is limited to one without a curve in the center line, and the hollow container formed from the parison is also necessarily limited to a shape in which the opening is located at the center of the container. Furthermore, even if it were possible to form a deformed parison with bent sides, it would be difficult to stretch such a parison in the axial direction, and from this point of view it is difficult to form a deformed hollow container by stretch blow molding. .

This invention was devised to solve the above-mentioned problems in injection stretch blow molding, and its purpose is to transform a parison into a deformed hollow container whose opening is largely deviated from the center of the container or inclined. The objective is to provide a new molding method that can perform stretch blow molding.

[Means for Solving the Problems] This invention for the above-mentioned purpose involves injection molding a bottomed parison with a straight center line, stretching the barine in the axial direction, and then applying external pressure to the sides of the parison to form the body. By forming a deformed parison that is bent from a required point, and then blow molding a deformed hollow container with the center of the opening shifted from the center of the main body from the deformed parison, it is possible to form a deformed hollow container even with injection stretch blow molding. Become.

The above-mentioned axial stretching of the parison may be carried out at fAm depending on the case.Also, before blow molding, the deformed parison is once pre-blown in a temperature-controlled mold, and the preform molded therein is blown into the deformed hollow container. It can also be molded.

[Function 1] In the above method, the injection-molded parison is bent to form a deformed parison, so there is no problem with the injection molding of the parison, and the bamboo to be formed into the deformed parison is not affected in the axial direction. Since stretching is performed, stretching can be easily performed, and even though the parison is injection molded, a biaxially oriented hollow container with a deformed opening can be molded.

[Example] Fig. 1 First, a parison 1 with a straight center line and a bottom made of thermoplastic resin such as polyethylene terephthalate is injection molded using an injection mold of a normal structure.

FIG. 2 The mouth part 2 of the parison 1 is held between the lip molds 3, and a core 5 having a freely movable stretching rod 4 in the center is inserted into the mouth part 2 from inside the lip mold.

At this time, the parison temperature is 105° to 11° except for the mouth part 2.
Maintain in the 0°C range. In this state, the stretching rod 4 is stretched to stretch the body of the parison 1 by 1.3 times in the axial direction.

FIG. 3: Next, the stretching rod 4 is returned to its original position, and the molding member 6, which has been set in advance so as to be able to rise and fall below the stretching position, is moved upward to press the body of the parison laterally.

This molded member 6 is formed with a block whose side surface facing the parison is inclined at an angle of about 35 degrees, and the temperature of the parison is kept at 90°C so that the temperature of the parison does not drop partially when the parison is pressed.
What temperature should it be heated to?

The body of the parison is pressed laterally sequentially from the bottom to the upper side along the inclined side surface of the molded member 6, and is bent at an angle of 35 degrees to form a deformed parison 7.

After the molding of the deformed parison 7 is completed, the core 5
is pulled out from the lip mold 3 together with the stretching rod 4, and the molded member 6 is lowered and returned to its original position.

With the removal of the molded member 6, the bent portion of the deformed parison 7 also returns to its original state, but this return angle remains at about 5 degrees, leaving the deformed parison 7 with the body section inclined at about 30 degrees. .

FIG. 4 The deformed parison 7 is transferred to the blow mold 8 with the mouth portion 2 held between the lip mold 3.

The blow mold 8 has a split mold that opens and closes laterally, and a bottom mold 10 is provided at the bottom of the cavity 9. Further, the cavity 9 is provided at an angle of 30 degrees except for the part that becomes the mouth part, and after the deformed parison 7 is placed in the center of the cavity 9, the mold is closed.

A blowing core 11 is inserted into the mouth portion 2 through the lip mold 3, and after the mold is clamped, air is blown into the deformed parison from the blowing core 11 at high pressure. The deformed parison 7 is expanded into a cavity cup by air pressure, as shown by the chain line, and becomes a hollow container 12.

After the mold is opened after blow molding and the blow core 9 is fired, the hollow container 12 is transferred together with the lip mold 3 to the removal position.

FIG. 5 In the above-mentioned hollow container 12, the opening 2 of the parison becomes the opening of the container, and the opening 2 is formed at a position largely offset from the center of the flat container body and inclined outward. It becomes a deformed hollow container.

In the above process, if temperature control of the parison is required, the temperature control is preferably carried out during stretching of the parison.

FIG. 6 shows this state, in which a temperature control pot 13 is placed in advance at the stretching position so as to be movable up and down, and during stretching, the temperature control pot 13 is raised to house the parison 1 in the pot. Stretching under temperature control prevents a decrease in temperature due to thinning, and also equalizes differences in temperature by external heat. Therefore, the temperature control effect is improved compared to when temperature control is performed before and after stretching.

The stretched and temperature-controlled parison 1 is then formed into a deformed parison 7 at the next location.
If the molding member 6 can be movably disposed to the side of the parison so as not to interfere with the molding member 6, secondary molding into the deformed parison 7 can be performed at that position after temperature adjustment.

Further, the hollow container 12 may be blow-molded after blow-blowing the deformed parison 7.

FIGS. 7 and 8 show a case where both the secondary forming and the blow-blowing of the parison are performed at the same location, and a pre-blowing mold 14 that opens and closes in the lateral direction is arranged at the stretching position, and the above-mentioned forming The member 6 is arranged so as to be able to move up and down.

The shaping into the deformed parison 7 is as shown in FIG.
After stretching, the forming member 6 is raised at the center of the pre-blow mold 14 in the open state.

When the molding is completed, the molding member 6 is lowered to an angle of 80° to 110°.
The pre-blow mold 14 whose temperature is controlled to ℃ is closed.

FIG. 8 After mold clamping, air is blown into the deformed parison 7 located at the center of the cavity 16 from the air passage 15 formed between the core 3 and the stretching rod 4 to form the preform 17. Shape.

After opening the mold, this preform 17 is transferred to the blowing mold,
A hollow container 12 as shown in FIG. 5 is formed from the preform 17.
Blow molding.

Molding of such deformed hollow containers is carried out by the hot parison method, in which injection molding of the parison and stretch blow molding are successively carried out, and the cold parison method, in which the injection molded parison is temporarily suspended, and then the parison is heated for 1 m and stretch blow molded. Either method can be adopted.

Further, the shape of the container is not limited to that shown in the drawings, and containers of various shapes can be formed using the same process.

[Effects of the Invention] As described above, the present invention stretches an injection-molded parison with a bottom in the axial direction and then secondary-forms it into a deformed parison, and with the deformed parison, it is possible to prevent the opening from being largely displaced from the center of the container. Alternatively, since the tilted deformed hollow container is blow-molded, no special mold or technique is required for injection molding of the parison, and the injection molding of the parison can be performed in the same manner as when molding a normal parison. . In addition, since the deformed parison has already been stretched in the axial direction, even if the hollow container is formed by blow molding, the resin forming the container body will be bidirectionally oriented, similar to a normal biaxially oriented container. It has excellent strength and transparency.

Furthermore, it is easy to control the temperature of the parison and brie-blow it.
By molding the preform, it has the advantage that hollow containers with shapes that are difficult to mold can be molded from the deformed parison.

[Brief explanation of drawings]

The drawings illustrate the method for molding a deformed hollow container according to the present invention, and FIGS. 1 to 4 are partial cross-sectional views sequentially explaining the molding process, and FIG. 5 is a cross-sectional view of the molded deformed hollow container.
FIG. 6 is a sectional view during temperature control, and FIGS. 7 and 8 are sectional views showing the blow molding process. 1... Parison 3... Lip type 5... Core 7... Deformed parison 9... Cavity 12... Deformed Hollow container 14... Brill blow mold 17... Preform 2... Mouth part 4... Stretching rod 6... Molding member 8... ... Blow mold 11 ... Blow core 13 ... Temperature control bot 16 ... Cavity

Claims (3)

[Claims] (1) A bottomed parison with a straight center line is injection molded, the parison is stretched in the axial direction, and external pressure is applied to the sides of the parison to form a deformed parison with the body bent at a required point, A method for forming a deformed hollow container, which comprises blow molding the deformed parison into a deformed hollow container in which the center of the mouth part is largely deviated or inclined from the center of the main body. (2) In the method for forming a deformed hollow container according to paragraph 1,
A method for forming a deformable hollow container, characterized in that temperature is controlled during axial stretching of the parison. (3) In the method for forming a deformed hollow container according to paragraph 1,
A method for molding a deformed hollow container, which comprises pre-blowing the deformed parison in a temperature-controlled mold before the blow molding.