JP6727760B2 - Hollow container manufacturing method and blow molding apparatus - Google Patents

Description

The present invention relates to a method for manufacturing a hollow container filled with a liquid such as a beverage and a blow molding device.

BACKGROUND ART Conventionally, as a hollow container (bottle) filled with various liquids such as beverages, for example, a hollow container formed of a resin material such as polyethylene terephthalate (hereinafter referred to as PET) has been adopted.

As a method for producing a hollow container made of a resin material, for example, a preform injection-molded into a bottomed cylinder is heated in a temperature capable of exerting a stretching effect, and is stretched in an axial direction by a stretching rod. At the same time, a method of blow molding with a pressurized gas (blow air) to stretch and deform in the radial direction is generally used.

Further, in recent years, various methods of blow molding a preform with a pressurized liquid instead of the pressurized gas have been proposed (see, for example, Patent Document 1).

JP, 2013-132861, A

However, when the hollow container is formed by blow molding with a pressurized liquid as in the method described in Patent Document 1, there is a possibility that the thickness distribution of the hollow container may vary. For example, a liquid has a larger heat capacity than a gas, and a liquid may have a slower flow velocity than a gas. Therefore, in blow molding with a pressurized liquid, compared with the case of blow molding with a pressurized gas, the meat of a hollow container The thickness distribution tends to be non-uniform. Further, in the method of Patent Document 1, if the bottle ruptures during the process of blowing the preform, the pressurized liquid that is the blowing medium will be scattered inside and outside the blow molding device. This causes the recovery work to take a long time and also causes a reduction in the operation rate of the device.

The present invention has been made in view of the above circumstances, and provides a method for manufacturing a hollow container and a blow molding apparatus capable of achieving a uniform wall thickness distribution even when blow molding with a pressurized liquid is performed. With the goal.

A first aspect of the present invention for solving the above-mentioned problems is an intermediate molding step of blow molding a preform with a pressurized gas to form an intermediate molded article, and a final molding by blow molding the intermediate molded article with a pressurized liquid. And a final molding step of forming a hollow container which is a molded product.

A second aspect of the present invention is the method for manufacturing a hollow container according to the first aspect, wherein in the final molding step, the intermediate molded article is blow molded with a pressurized liquid in a first blow mold, and the intermediate molding is performed. In the step, the method for producing a hollow container is characterized in that the preform is blow-molded by a pressurized gas in a second blow mold different from the first blow mold.

A third aspect of the present invention is the method for manufacturing a hollow container according to the first aspect, wherein in the final molding step, the intermediate molded article is blow molded with a pressurized liquid in a first blow mold, and the intermediate molding is performed. Also in the step, there is a method for producing a hollow container, characterized in that the preform is blow-molded by a pressurized gas in the first blow mold.

A fourth aspect of the present invention is the method for manufacturing a hollow container according to any one of the first to third aspects, wherein in the intermediate forming step, the preform is blow-molded with a pressurized gas, and is blown more than the hollow container. A method of manufacturing a hollow container, comprising forming a primary blow-molded product of a large size and then shrinking the primary blow-molded product to a size smaller than the hollow container to form the intermediate molded product.

A fifth aspect of the present invention is an intermediate molding part that blow-molds a preform with a pressurized gas to form an intermediate molded product, and a hollow molded product that is a final molded product blow-molded with the pressurized liquid. A final molding unit for forming a container, and a molding device for a hollow container.

According to a sixth aspect of the present invention, in the hollow container molding apparatus according to the fifth aspect, the final molding section includes a first blow mold for molding the intermediate molded article with a pressurized liquid, and the intermediate molding section is provided. Is a molding apparatus for a hollow container, comprising a second blow mold different from the first blow mold for molding the preform with pressurized gas.

In the present invention, since the preform is blow-molded by the pressurized gas (blow air) to form the intermediate molded product, the intermediate molded product is blow-molded by the pressurized liquid, so that the final molded product is hollow. The thickness of the container can be made uniform. That is, the thickness distribution of the intermediate molded product blow-molded by the pressurized gas is almost uniform, so by blow molding this intermediate molded product with a pressurized liquid, a hollow container with a uniform wall thickness distribution is manufactured. can do.

It is a schematic explanatory drawing which shows the molded product obtained in each process of the manufacturing method of the hollow container which concerns on Embodiment 1 of this invention. 1 is a block diagram showing a schematic configuration of a blow molding device according to Embodiment 1. FIG. FIG. 3 is a schematic diagram illustrating a method for manufacturing the hollow container according to the first embodiment. FIG. 6 is a block diagram showing a schematic configuration of a blow molding device according to a second embodiment. 7A and 7B are schematic diagrams illustrating a method for manufacturing a hollow container according to the second embodiment.

The present invention relates to a method for producing a hollow container by a so-called two-stage blow method and a blow molding apparatus, which comprises blow molding with a pressurized gas (pressurized gas) and blow molding with a pressurized liquid (pressurized liquid). It is characterized in that a hollow container is molded.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
In the method for manufacturing a hollow container according to the present embodiment, as shown in FIG. 1, a preform 10 formed by injection molding, a primary blow molded product 20, an intermediate molded product 30, and a hollow container 40 which is a final molded product. To mold.

The hollow container 40 is, for example, a heat-resistant bottle filled with a liquid such as a beverage, and is made of a resin material such as PET. In the present embodiment, a hollow portion 40 of the hollow container 40 is formed with a recess 42 in the circumferential direction, and a bottom portion 43 is formed with an upper bottom portion 44 projecting inward of the container.

A blow molding apparatus 100 for molding such a hollow container 40 linearly forms molded products (preform 10, primary blow molded product 20, intermediate molded product 30, and hollow container 40) as shown in FIG. This is a linear transport type device for transporting, and has five stations (injection molding unit 120, temperature control unit (heating unit) 130, intermediate molding unit 140, final molding unit 150, and unloading unit 160 to which the injection device 110 is connected (process). ) Is provided. The injection molding unit 120 and the temperature control unit 130 may be divided into stations so that they are independent from each other. Further, if necessary, a station for crystallizing the neck portion of the preform 10 may be installed between the injection molding unit 120 and the temperature control unit 130.

The injection molding unit 120 molds the preform 10 with the resin material injected from the injection device 110 (injection step). The injection molding unit 120 includes an injection molding die 121 connected to the injection device 110, as shown in FIG. The injection mold 121 includes an injection cavity mold 122 that defines the outer surface of the body of the preform 10 and a core mold 123 that defines the inner surface of the preform 10. A neck mold 124, which is a split mold that can be opened and closed in the horizontal direction and defines the outer wall surface of the neck portion of the molded product, is provided above the injection mold 121. Then, the resin material (for example, PET resin) which is a raw material is filled into the injection cavity mold 122 through the gate 125 provided at the center of the bottom of the injection cavity mold 122 to form the preform 10. The preform 10 injection-molded in this manner is conveyed to the temperature control unit 130 while being held by the neck mold 124.

In the temperature adjustment unit 130, the temperature of the preform 10 is adjusted before the blow molding in the intermediate molding unit 140 (temperature adjustment process). As shown in FIG. 3B, the temperature adjustment unit 130 includes, for example, a plurality of rod-shaped heaters 131 arranged at predetermined intervals in the axial direction of the preform 10, and the rod-shaped heaters 131 allow the resin material ( The temperature is adjusted so that the temperature is equal to or higher than the proper stretching temperature of the PET resin (about 100 to 120° C.). The preform 10 heated to a predetermined suitable drawing temperature is then conveyed to the intermediate molding unit 140.

In the intermediate molding part 140, the intermediate molded product 30 is formed from the preform 10 through the primary blow molded product 20 (intermediate molding process). As shown in FIG. 3C, the intermediate molding section 140 includes a primary blow molding die (second blow die) 141. The primary blow molding die 141 includes an openable/closable primary blow molding split die 142, a stretch rod 143 that is vertically movable through a blow core die (not shown), and a primary blow bottom die 144. Although not shown, the intermediate molding unit 140 includes a supply unit that supplies pressurized gas via a blow core mold.

Then, in the intermediate molding part 140, the preform 10 arranged in the primary blow molding die 141 is stretched in the vertical axis direction by the stretching rod 143, and crystallized by the pressurized gas (high pressure air) supplied from the supply part. By stretching in the radial direction until it comes into contact with the inner wall surface of the primary blow molding die 141 heated to a predetermined temperature equal to or higher than the temperature, for example, 140° C. to 180° C., the length in the vertical axis direction and the radial direction is the final molded product. A primary blow-molded product 20 larger than a hollow container 40 is formed. At this time, the residual stress of the resin material (PET resin) is relaxed, and the crystallization density is improved (heat resistance is improved by heat setting treatment). The primary blow-molded product 20 thus formed by blow molding with a pressurized gas has a substantially uniform wall thickness distribution.

After that, the primary blow-molded product 20 is contracted when the pressurized gas is exhausted and taken out from the primary blow-molding die 141 to lower the temperature (mainly during exhaust), and the primary blow-molded product 20 is blown from the hollow container 40 which is the final molded product. Becomes a slightly smaller intermediate molded product 30 (FIG. 3(d)).

As described above, since the thickness distribution of the primary blow-molded product 20 is substantially uniform, the thickness distribution of the intermediate molded product 30 in which the primary blow-molded product 20 is slightly shrunk does not greatly vary. Then, the intermediate molded product 30 is conveyed to the final molding unit 150 while being held by the neck mold 124.

In the final molding part 150, the hollow container 40 which is the final molded product is formed by blow molding the intermediate molded product 30 with a pressurized liquid (final molding step). The final molding unit 150 includes a final blow molding die (first blow mold) 151, as shown in FIG. The final blow molding die 151 includes an openable/closable final blow molding split mold 152 and a final blow bottom mold 153. The final blow molding split mold 152 has an inner wall surface that follows the outer shape of the hollow container 40. That is, on the inner wall surface of the final blow molding split mold 152, a convex portion 154 that protrudes inward is provided at a position corresponding to the concave portion 42 of the hollow container 40. Although not shown, the final molding unit 150 includes a supply unit that supplies the pressurized liquid via a blow core mold.

Then, although not shown, the pressurized liquid is supplied from the supply unit through the blow core mold to the inside of the intermediate molded product 30 arranged in the final blow molding mold 151 to reach a predetermined temperature (for example, about 115° C.). The intermediate molded product 30 is stretched in the vertical axis direction and the horizontal axis direction until it comes into contact with the inner wall surface of the heated final blow molding split mold 152. As a result, the hollow container 40, which is the final molded product, is molded.

The hollow container 40 is then transported to the take-out section 160 and taken out of the apparatus from the take-out section 160.

As described above, in this embodiment, the hollow container 40 is manufactured from the preform 10 by the so-called two-stage blow method. Therefore, the shapeability of the hollow container 40 is improved as compared with the case where the hollow container 40 is manufactured by the one-stage blow method. For example, the recess 42 can be favorably formed in the body 41 of the hollow container 40. Further, the hollow container 40 having excellent heat resistance can be realized.

Further, in the present embodiment, the hollow container 40 is formed by blow molding the intermediate molded product 30 with a pressurized liquid. However, the intermediate molded product 30 (primary blow molded product 20) is prepared by pressing the preform 10 into a pressurized gas. It is formed by blow molding. Therefore, the thickness distribution of the hollow container 40 can be made uniform.

That is, the intermediate molded product 30 blow-molded with the pressurized liquid is formed by blow molding with the pressurized gas, and the thickness distribution thereof is substantially uniform. The intermediate molded product 30 has a size close to that of the hollow container 40, which is the final molded product, and has a low draw ratio during blow molding with a pressurized liquid. Therefore, according to the manufacturing method of the present embodiment, the wall thickness distribution of the hollow container 40 can be made uniform even by blow molding with a pressurized liquid. In addition, in the present embodiment, the site where the bottle may rupture is limited to the intermediate molding section 140 in which the blow medium is pressurized gas. Therefore, when the rupture of the bottle is detected by reducing the pressure of the pressurized gas or the like, the subsequent operation of the final molding unit 150 can be stopped in advance, and there is a drawback such as the scattering of the liquid inside and outside the device that can occur in Patent Document 1. Is also resolved.

The liquid used in the final molding step (blow molding) is not particularly limited, but it is preferable to use the content liquid (for example, beverage) finally filled in the hollow container 40. Thereby, the final molding process of the hollow container 40 and the filling process of the content liquid can be performed at the same time, and the production line can be simplified.

(Embodiment 2)
FIG. 4 is a block diagram showing a schematic configuration of a blow molding device according to the second embodiment, and FIG. 5 is a schematic diagram showing a method for manufacturing a hollow container according to the second embodiment.

As shown in FIG. 4, the blow molding apparatus 100A according to the present embodiment is a so-called rotary conveyance type apparatus, and the injection molding unit 120, the temperature control unit 130, the blow molding unit 170, and the take-out unit 160 are not shown. Are arranged around the rotary transport device along the transport direction.

The injection molding unit 120, the temperature control unit 130, and the take-out unit 160 are the same as those in the first embodiment, and thus the description thereof is omitted here.

The blow molding unit 170 is a station that also serves as the intermediate molding unit 140 and the final molding unit 150 described in the first embodiment. That is, in the blow molding part 170, the primary blow molded product 20 (intermediate molded product 30) is formed by blow molding the preform 10 with pressurized gas, and the intermediate molded product 30 is blow molded with the pressurized liquid. The hollow container 40, which is the final molded product, is formed.

As shown in FIG. 5, the blow molding unit 170 includes a blow molding die (first blow die) 171. The blow molding die 171 includes a blow molding split die 172 that can be opened and closed, a stretch rod 173 that can move up and down through a blow core die (not shown), and a blow bottom die 174. Note that the blow molding split mold 172 has an inner wall surface along the outer shape of the hollow container 40, like the final blow molding split mold 152 described above. Although not shown, a supply unit for supplying each of the pressurized gas and the pressurized liquid via the blow core type is provided.

In the method for manufacturing a hollow container according to this embodiment, the preform 10 is injection-molded by the injection molding unit 120 (see FIG. 3A), and the preform 10 is heated by the temperature adjusting unit 130 (FIG. 3). (See (b)), the preform 10 is conveyed to the blow molding unit 170 and placed in the blow molding die 171.

In the blow molding unit 170, as shown in FIG. 5A, first, the preform 10 placed in the blow molding die 171 is stretched in the vertical axis direction by the stretching rod 173, and the pressure supplied from the supply unit is applied. A primary blow-molded product 20 having the same outer shape as the hollow container 40 is formed by radially expanding the inner wall surface of the blow molding die 171 heated to a predetermined temperature with gas (high-pressure air). ..

Thereafter, as shown in FIG. 5(b), the pressurized gas is exhausted from the inside of the primary blow-molded product 20. At that time, the primary blow-molded product 20 contracts slightly, and the primary blow-molded product 20 slightly shrinks from the hollow container 40 which is the final molded product. A small size intermediate molded product 30 is formed.

Then, the intermediate molded product 30 is further blow-molded in the blow mold 171 to form the hollow container 40 as the final molded product. Specifically, as shown in FIG. 5( c ), with the stretch rod 173 inserted in the intermediate molded product 30, inside the intermediate molded product 30, a blow core mold (not shown) is supplied from the supply unit. A pressurized liquid is supplied through the intermediate molded product 30 until it comes into contact with the inner wall surfaces of the blow molding split mold 172 and the blow bottom mold 174 heated to a predetermined temperature (for example, about 115° C.). As a result, the hollow container 40, which is the final molded product, is molded.

After that, as in the first embodiment, the hollow container 40 is transported to the take-out section 160 and taken out of the apparatus through the take-out section 160.

As described above, in this embodiment, the blow molding with the pressurized gas and the blow molding with the pressurized liquid are performed in one blow molding die 171, so that the blow molding apparatus used for manufacturing the hollow container 40 is used. Can be simplified. Further, the manufacturing method according to the present embodiment is also a so-called two-stage blow method, so that the hollow container 40 having excellent heat resistance can be realized. Further, the shapeability of the hollow container 40 can be improved.

In the present embodiment, when the pressurized liquid is supplied into the intermediate molded product 30, the stretch rod 173 is held in the intermediate molded product 30, but the stretch rod 173 is pulled out. It may be in a state.

Although one embodiment of the present invention has been described above, of course, the present invention can be variously modified without departing from the scope of the invention.

For example, in the above-described embodiment, the blow molding device is illustrated as including the injection molding unit, but the injection molding unit may not necessarily be provided. For example, a preform injection-molded in advance may be supplied to the temperature control unit, and the temperature control unit may adjust the temperature to a predetermined temperature.

10 Preform 20 Primary Blow Molded Product 30 Intermediate Molded Product 40 Hollow Container 41 Body 42 Concave 43 Bottom 44 Upper Bottom 100,100A Blow Molding Device 110 Injection Device 120 Injection Molding Part 121 Injection Molding Mold 122 Injection Cavity Mold 123 Core Mold 124 Neck type 125 Gate 130 Temperature control part 131 Rod heater 140 Intermediate molding part 141 Primary blow molding mold 142 Primary blow molding split mold 143 Stretching rod 144 Primary blow bottom mold 150 Final molding part 151 Final blow molding mold 152 Final blow molding split mold 153 Final blow bottom mold 154 Convex part 160 Extraction part 170 Blow molding part 171 Blow molding mold 172 Blow molding split mold 173 Stretching rod 174 Blow bottom mold

Claims (3)

An intermediate molding step of forming an intermediate molded article by blow molding a preform placed in a blow molding die for intermediate molding with pressurized gas;
And a final forming step for forming a hollow container which is the final molded article by blow molding by the positioned within a blow mold for final forming said intermediate molded article pressurized liquid,
In the final molding step, the intermediate molded product is blow-molded with a pressurized liquid in a first blow mold that is a blow molding mold for final molding,
In the intermediate molding step, the preform is blow-molded by a pressurized gas in a second blow mold which is a blow molding mold for intermediate molding different from the first blow mold. A method for producing a hollow container characterized by the above . Claim1In the method for producing a hollow container according to
In the intermediate molding step, the preform is blow-molded with pressurized gas to form a primary blow-molded product having a size larger than the hollow container, and then the primary blow-molded product is shrunk to a size smaller than the hollow container. To form the intermediate molded product.
A method for manufacturing a hollow container characterized by the following:.. An intermediate molding part for forming an intermediate molded product by blow molding a preform placed in a blow molding die for intermediate molding with pressurized gas,
And a final molding section for forming a hollow container which is the final molded article by blow molding are arranged in the blow mold for final forming said intermediate molded article in pressurized liquid, was closed,
The final molding unit includes a first blow mold that is a blow molding mold for the final molding that molds the intermediate molded product with a pressurized liquid,
The intermediate molding unit includes a second blow mold that is a blow molding mold for the intermediate molding different from the first blow mold that molds the preform with a pressurized gas. An apparatus for forming a hollow container, characterized by:

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