JP2013154617A - Blow molding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control at a high level of accuracy, a temperature of liquid supplied in a preform to expand the preform in an expansion state, in a blow molding apparatus that uses the liquid as a pressurized fluid.SOLUTION: A blow molding device is provided with a blow nozzle which is tightly fitted into the mouth tube part of a preform while the preform is mounted in a die. The blow molding device is also provided with a pressurized-liquid supply part. A pressurized liquid is supplied from the pressurized-liquid supply part into the preform through the blow nozzle, and a container is formed in an expanded shape to follow the shape of the cavity of the die. A valve mechanism is disposed at the downstream end of a supply path to be able to open and close the supply path, the supply path being located within the blow nozzle and to supply the liquid. The valve mechanism is configured so that, when the valve mechanism is in a closed state, the liquid can be circulated between the supply path and the pressurized-liquid supply part, and when the valve mechanism is in an open state, the pressurized liquid can be supplied into the preform through the supply path.

Description

The present invention relates to a blow molding apparatus for a synthetic resin preform using a liquid as a pressurized fluid.

Blow-molded casings (so-called PET bottles) made of polyethylene terephthalate (PET) resin exhibit many excellent characteristics, and are therefore used in various fields as casing containers.
This type of container is generally molded by expanding and deforming a preform that has been injection-molded into a bottomed cylindrical shape in an expanded state in a state where the preform is heated to a temperature at which a stretching effect can be exhibited. .

That is, as shown in FIG. 5 (corresponding to FIG. 12 of Document 1), the preform 31 heated to a temperature at which the stretching effect is exerted is protruded upward from the mouth tube portion 32, and the mouth of the preform 31 is The neck ring 33 integrally provided at the lower end of the outer peripheral surface of the cylindrical portion 32 is attached to the blow mold 101 in a state where the neck ring 33 is locked to the neck support collar 103,
In a state where the guide tube portion 110 which is the tip portion of the blow nozzle 104 is loosely fitted into the mouth tube portion 32 of the preform 31,
Along with the stretching rod 108 inserted through the insertion hole 111 penetratingly formed in the center of the blow nozzle 104, it is stretched in the axial direction through the insertion hole 111, and stretched in the radial direction with the blown air as the pressurized fluid, to the housing 41. To achieve molding.

Patent Document 2 describes an invention relating to a method of blow molding a preform using a liquid instead of blow air as a pressurized fluid.
In such a molding method, if the content liquid that is finally filled in the product such as beverages, cosmetics, and medicines is used as the liquid, the filling process can be omitted and the production line can be simplified. Become.

JP 2003-251685 A JP 2000-43129 A

In blow molding using a liquid as a pressurized fluid described in Patent Document 2, the portion excluding the mouth tube portion of the preform is preheated to a temperature suitable for stretched blow molding, and the pressurized liquid is pressed. It is supplied into the reform and stretched into an expanded shape to shape the container, but in the case of liquid, heat conduction with the preform is greater than that of gas, and the temperature of the preform varies greatly depending on the temperature of this liquid. Therefore, it is necessary to control the temperature of the liquid supplied into the preform with high accuracy.
Here, if there is a variation in the temperature of the liquid to be supplied, the temperature of the preform to be stretched changes depending on the temperature of the liquid, and the stretchability changes, resulting in variations in performance such as strength and heat resistance of the container. In some cases, sufficient formability cannot be obtained.

FIG. 6 is a schematic explanatory diagram of a conventional blow molding apparatus for blow molding a preform using a liquid instead of blow air as a pressurized fluid.
The main part A of this apparatus has a mold 1 and a blow nozzle 104, and a pressurized liquid supply part 122 and a liquid circulation part 123 are arranged as accessory equipment for supplying a pressurized fluid adjacent to the main part A. doing.

  The pressurized liquid supply unit 122 is in the form of a plunger pump, which operates using a pressurized fluid Fp supplied from a pressurizing device 121 such as a pressurized pump or a compressor via a pipe P1 as a power source, and supplies pressurized liquid L. Through the pipe P2 and the electromagnetic valve V101, the blow nozzle 104 is supplied to the inside of the preform 31 that is closely fitted to the tip of the blow nozzle 104, and the preform 31 is expanded along the cavity shape of the mold 1. The container 41 is shaped.

The liquid circulation device 123 circulates the liquid L through the pipe R102 and the pipe R103, and supplies the liquid L adjusted to a predetermined temperature to the pressurized liquid supply unit 122 while replenishing the liquid L from the pipe R101. Supply
Since the pressurized liquid L is supplied to the interior of the preform 31 through the pipe P2 and the blow nozzle 104 as described above, the temperature of the pressurized liquid L depends on many factors such as the room temperature at the site where the apparatus is disposed and the number of molding shots. Will change.
Blow molding includes (1) a step of setting the preform 31 on the mold 1, (2) a step of fitting the blow nozzle 104 into the mouth tube portion 32 of the preform 31, and (3) a pressurized liquid L To the inside of the preform 31 through the blow nozzle 104 to shape the container 41, (4) the step of detaching the blow nozzle 104 from the mouth tube portion 32 of the preform 31, and (5) the mold 1 There are many processes, such as a process of opening the mold and taking out the container 41,
Among these, the liquid L is introduced into the blow nozzle for the first time in the step (3) and immediately discharged into the preform 31 or the container 41, so that the liquid L supplied into the preform 31 is supplied. It has been a difficult technical matter in actual production to keep the temperature constant.

Therefore, the present invention is a blow molding apparatus that uses a liquid as a pressurized fluid, and it is a technical problem to accurately control the temperature of the liquid supplied into the preform in order to stretch the preform in an expanded state. To do.

The main configuration of the present invention for solving the above problems is as follows.
It has a blow molding die and a blow nozzle that fits tightly into the preform tube portion with a bottomed cylindrical preform attached to the die, and a pressurized liquid supply part is provided. In the blow molding apparatus for supplying the pressurized liquid from the pressurized liquid supply unit into the preform through the blow nozzle, and forming the container in an expanded state along the cavity of the mold,
A valve mechanism is disposed at the downstream end of the liquid supply path in the blow nozzle so that the supply path can be opened and closed.
The valve mechanism is configured so that liquid can be circulated through the supply path and the pressurized liquid supply unit in the closed state, and the pressurized liquid can be supplied into the preform through the supply path in the open state. It is.

According to the apparatus having the above configuration, among all the processes of blow molding from the process of setting the preform to the mold to the process of removing the molded container from the mold,
In other processes except for the process of supplying pressurized liquid to the interior of the preform through the supply path and shaping the container, the liquid used as the pressurized fluid is pressurized with the supply path as needed. It can be circulated between the liquid supply unit and adjusted to a predetermined temperature,
The temperature of the liquid supplied into the preform for shaping the container can be controlled with high accuracy, and the shaping of the container can be stably achieved under a certain temperature condition. It is possible to effectively solve problems such as variations in performance such as heat resistance, and inability to obtain sufficient formability without impairing productivity.

  Here, by arranging the valve mechanism at the downstream end portion of the supply path communicating with the preform formed in the blow nozzle, the temperature is circulated through most of the liquid staying in the supply path. The temperature of the liquid can be adjusted and can be maintained at a predetermined temperature with high accuracy.

In another aspect of the present invention, in the main configuration described above, the pressurized liquid supply unit is provided with a liquid circulation unit that adjusts the pressure to a predetermined temperature and supplies the liquid.
The supply path communicates with the pressurized liquid supply section through an introduction path disposed at the upstream end of the supply path of the blow nozzle so as to be openable and closable, and is disposed at the upstream end of the valve mechanism at the downstream end. It shall communicate with the liquid circulation part so as to be openable and closable via a discharge path provided,
In a closed state of the valve mechanism, it is configured to enable liquid circulation between the supply path and the pressurized liquid supply unit via the liquid circulation unit,
The present invention relates to a configuration for circulating a liquid between a supply path and a pressurized liquid supply unit.

Still another configuration of the present invention is the above main configuration,
A rod-shaped seal pin is inserted and disposed in the low nozzle so as to be movable in the axial direction of the blow nozzle, and the supply path is brought into contact with the seal step provided on the inner peripheral surface of the blow nozzle at the tip of the seal pin Is configured to be closed,
It is said that the valve mechanism is configured by contacting and uncontacting the tip end portion of the seal pin with the seal stepped portion.

  The above configuration relates to a valve mechanism that opens and closes the supply passage in the blow nozzle, and easily opens and closes the supply passage by the movement operation of a stick-shaped seal pin that is inserted and movably moved in the axial direction of the blow nozzle. be able to.

  Still another configuration of the present invention is that, in the above configuration, a rod is inserted into a cylindrical rod-like shaft body so as to be slidable in a liquid-tight manner to form a seal pin.

The rod that is slidably inserted into the rod-shaped shaft body in a liquid-tight manner can be moved in a mode different from the movement operation of the shaft body, and this rod was used as a pressurized fluid for blow molding. A head space in a container filled with a liquid as a product simultaneously with shaping can be used as a member for controlling the head space to a predetermined amount.
It can also be used as a stretching rod for longitudinally stretching a preform.

The blow molding apparatus of the present invention has the above-described configuration.
According to the apparatus having the main configuration of the present invention, the pressurized liquid is supplied from the step of setting the preform to the mold to the step of removing the molded container from the mold. In other processes except for the process of supplying the inside of the preform and shaping the container, the liquid used as the pressurized fluid is always or between the supply path and the pressurized liquid supply unit as necessary. It can be circulated and adjusted to a predetermined temperature,
The temperature of the liquid supplied into the preform for shaping the container can be controlled with high accuracy, and the shaping of the container can be achieved stably under certain temperature conditions, and the strength and heat resistance of the container It is possible to effectively solve problems such as variations in performance and the like, in which sufficient formability cannot be obtained without impairing productivity.

It is a schematic explanatory drawing which shows an example of the whole structure of the blow molding apparatus of this invention. It is sectional drawing to which the lower half part of the main part of the apparatus of FIG. 1 was expanded. It is sectional drawing which shows the state which extended the preform in the expanded state with the pressurized liquid among the shaping | molding processes by the apparatus of FIG. 1, and shaped the container. It is sectional drawing which shows the state which removed the rod from the state of FIG. 3 among the formation processes by the apparatus of FIG. It is sectional drawing which shows the principal part of an example of the blow molding apparatus by the conventional blow air. It is a schematic explanatory drawing which shows the prior art example of the blow molding apparatus by a pressurized liquid.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described along examples with reference to the drawings.
1 to 4 are for explaining an embodiment of the blow molding apparatus of the present invention, and further explaining a blow molding method using this apparatus.
First, the overall configuration of the apparatus will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic explanatory view showing an example of the overall configuration of the blow molding apparatus of the present invention, and FIG. 1 is an enlarged cross-sectional view of the lower half of the main part of the apparatus shown in a vertical cross section, and FIG.

FIG. 1 shows a state in which a preform 31 is attached to the mold 1 and the tip of the blow nozzle 4 is fitted into the mouth tube portion 32 of the preform 31.
The shape of the preform 31 to be used is a bottomed cylindrical test tube as a whole, and a mouth tube portion 32 is erected at the upper end portion, and a neck ring 33 is disposed at the lower end portion of the mouth tube portion 32, The mouth tube portion 32 is mounted in the mold 1 in a state of protruding outward (upward in FIGS. 1 and 2).

The main part of this apparatus has a mold 1, a partition member 11, and a blow nozzle 4, and a pressurizing device 21, a pressurized liquid supply unit 22, and a liquid circulation unit 23 are arranged as accessory equipment.
As shown in FIG. 2, the partition wall member 11 is disposed above the mold 1 so as to surround the outer peripheral surface of the mouth tube portion 32 of the preform 31 protruding above the mold 1 through the space S. Has been.
The partition wall member 11 is provided with a vent hole 13 for supplying pressurized gas to the space S as required.
Further, the support rod 12 provided around the lower end of the partition wall member 11 is brought into close contact with the neck ring 33 of the preform 31 from above to maintain the mounting posture of the preform 31.

The blow nozzle 4 has a tubular shape as a whole, and is composed of an insertion tube piece 5 and a supply tube portion 6 which are closely connected by a seal member 7b.
The fitting cylinder piece 5 has a cylindrical hollow portion inside, and as shown in FIG. 2, a circumferential step portion 5a having a diameter decreasing toward the tip is provided on the outer peripheral wall, and the cylindrical tip is provided. Is inserted into the mouth tube portion 32 of the preform 31, and the blow nozzle 4 and the mouth tube portion 32 are brought into contact with each other via the seal member (O-ring) 7 a on the upper end surface of the peripheral step portion 5 a and the mouth tube portion 32. They are connected in close communication.

The supply cylinder portion 6 is a member having a hollow cylindrical portion as a whole, and as shown in FIG. 1, an introduction path 6a for the liquid L is disposed through the peripheral wall at the upper end portion, and the lower end portion. In the vicinity, a discharge path 6b for the liquid L is also provided penetrating the peripheral wall.
Further, a seal step 6s inclined downward in a reduced diameter is provided on the inner peripheral surface of the lower end portion of the supply cylinder portion 6 further below the discharge passage 6b.
Further, a vent hole 6c for communicating the outside and the inside of the supply cylinder portion 6 is disposed under the seal step portion 6s.

Further, a rod-like seal pin 9 elongated in the axial direction (vertical direction in FIG. 1) is inserted and arranged in the blow nozzle 4 composed of the fitting cylinder piece 5 and the supply cylinder portion 6 as described above. Yes.
Here, the seal pin 9 is obtained by inserting an elongated cylindrical rod 8 into a slender cylindrical rod-shaped shaft body 9a so as to be slidable in a liquid-tight manner, and a short cylindrical seal is provided at the tip of the shaft body 9a. The tube piece 9t is fitted and assembled coaxially. And the outer peripheral edge part of the lower end surface of this seal cylinder piece 9t is rounded off, and becomes the taper edge part 9ta.

Further, the blow nozzle 4 and the seal pin 9 form a cylindrical supply path Fs communicating with the inside of the preform 31 along the axial direction of the blow nozzle 4 in the blow nozzle 4.
When the seal pin 9 is displaced downward, the taper edge 9ta of the seal cylinder piece 9t abuts on the seal step 6s provided around the inner peripheral surface of the lower end of the supply cylinder 6 as shown in FIGS. Thus, the communication of the supply path Fs to the inside of the preform can be closed, and the seal pin 9 can be opened by moving upward as shown in FIG. 3, and the taper edge 9ta of the taper edge 9ta can be opened. A valve mechanism Vm is configured by contact with and disengagement from the seal step 6s.
Here, the introduction path 6a described above is positioned at the upstream end of the supply path Fs, and the discharge path 6b is positioned at the downstream end of the supply path Fs and immediately upstream of the seal step 6s.

Moreover, the rod 8 is for exhibiting the function of controlling the head space in a container filled with a liquid L used as a pressurized fluid for blow molding at the same time as a product as described later to a predetermined amount.
Further, the rod 8 can be used as a stretching rod for longitudinally stretching the preform 31.

Next, looking at the attached equipment,
A pressurizing device 21, a pressurized liquid supply unit 22, and a liquid circulation unit 23 are disposed. The pressurizing device 21 has been conventionally an essential facility for blow molding, and has a large size such as a pressurizing pump or a compressor. The pressurized fluid Fp supplied from the pressurizing device 21 via the pipe P1 serves as a power source of the plunger pump-like pressurized liquid supply unit 22 that supplies the pressurized liquid L.
Of course, the pressurized liquid supply unit 22 may be a cylinder with a built-in piston having two chambers in addition to a pump-like one such as a plunger shown in the figure.

Further, the liquid circulation unit 23 adjusts the liquid L to a predetermined temperature while adjusting the liquid L to a predetermined temperature while replenishing the liquid L from the pipe R1 and supplying the liquid L to the pressurized liquid supply unit 22 through the pipe R2. However, it has a function of circulating between the pressurized liquid supply unit 22 and the supply path Fs in the blow nozzle 4.
That is, as necessary, the liquid L is referred to as supply path Fs → discharge path 6b → pipe R3 → liquid circulation part 23 → pipe R2 → pressurized liquid supply part 22 → pipe P2 → introduction path 6a → supply path Fs. The configured circuit CR can be circulated.

  The circulation path CR is provided with a number of valves for opening and closing the flow paths as needed along the blow molding process. In FIG. 1, four electromagnetic valves V1, V2, V3 and V4 are shown.

Next, a method for manufacturing a synthetic resin container using the blow molding apparatus described above, that is, a blow molding method will be described with reference to FIGS.
In blow molding, the steps described in the following (1) to (6) are sequentially performed.
(1) First, a preform 31 in which a portion excluding the mouth tube portion 32 is heated to a temperature suitable for blow molding is attached to the mold 1 for blow molding with the mouth tube portion 32 protruding upward, Clamp the mold.

(2) Next, the assembled and fixed partition member 11 and the blow nozzle 4 are lowered from above the mouth tube portion 31, and the tip end portion of the fitting tube piece 5 is fitted into the mouth tube portion 32, as shown in FIGS. State.
Here, the taper edge portion 9ta of the seal tube piece 9t constituting the tip portion of the seal pin 9 is brought into contact with the seal step portion 6s of the supply tube portion 6 to close the valve mechanism Vm, and further displace the rod 8 downward. The tip of the lever is inserted into the preform 31 by a predetermined length.
Further, the valves V1, V2, and V3 are all opened, and the liquid L circulates in the above-described circulation path CR while the temperature of the liquid L is adjusted by the liquid circulation unit 23.

(3) Next, as shown in FIG. 3, from the state of FIG. 1, the seal cylinder piece 9t is moved up and displaced along with the shaft body 9a constituting the seal pin 9 to open the valve mechanism Vm, and the valves V1, V2 are opened. , V3 is closed, and the circulation of the liquid L along the circulation path CR is stopped.
The liquid L pressurized by operating the pressurizing function of the pressurized liquid supply unit 22 is supplied from the supply path Fs to the inside of the preform 31 through the mouth tube portion 32, and the preform 31 is expanded in an expanded state. A container 41 is shaped along the cavity 2 of the mold 1.
In this process, when the diameter of the mouth tube portion 32 is deformed by the pressure of the liquid L, pressurized gas is introduced into the partition wall member 11 from the vent hole 13 provided in the partition wall member 11 through the pipe P3. Then, by pressurizing the space S surrounding the outer peripheral surface of the mouth tube portion 32, such a diameter expansion deformation can be effectively suppressed.

(4) Next, after the container 41 is shaped as described above, as shown in FIG. 4, the shaft body 9a is moved downward to close the valve mechanism Vm and open the valves V1, V2, and V3. As a result, the liquid L is circulated again along the circulation path CR.
(5) Simultaneously with the process of (4) or slightly, the tip of the rod 8 is removed from the container 41 as shown in FIG.
Here, all the liquid L remaining in the supply path Fs below the bubble mechanism Vm flows into the container 41 as the tip of the rod 8 is removed, and the liquid level Ls descends in the container 41. As shown in FIG. 4, it can be adjusted to a predetermined head space Hs set in advance.
Further, when the inside of the container 41 is in a decompressed state and the container 41 is deformed into a reduced volume during the insertion / removal operation of the distal end portion of the rod 8, the intake hole provided in the supply cylinder portion 6 of the blow nozzle 4 By opening 6c with the valve V4, the reduced pressure state in the container 41 can be relaxed, and the deformation of the container 41 as described above can be effectively prevented.

  (6) Although not shown, the blow nozzle 4 and the mouth tube portion 31 of the container 41 are disengaged, the mold 1 is opened, and the container 41 filled with the liquid L is taken out. The cylindrical portion 32 is sealed with a cap to obtain a product.

Here, in the blow apparatus described above or the molding method using this apparatus, an example in which the preform 31 is stretched in an expanded state with the pressurized liquid L to shape and mold the container 41 has been described.
The rod 8 is used as a stretching rod for longitudinally stretching the preform 31, and so-called biaxial stretching blow molding is performed in which longitudinal stretching by the rod 8 and expansion stretching by the pressurized liquid L are combined. You can also.

As mentioned above, although embodiment of the blow molding apparatus of this invention was described along the Example, of course, this invention is not limited to an above-described Example.
For example, in the above-described embodiment, the example in which the valve mechanism Vm is configured by contacting and detaching the tapered edge portion 9ta with the seal step portion 6s has been described. However, in consideration of sealing performance, operability related to opening and closing, and the like. Thus, various types of valve mechanisms can be employed.
Moreover, in the said Example, although it was set as the structure which adjusts the head space Hs of the filling liquid in the container 41 using the rod 8, it can also be set as the structure without the rod 8 according to the intended purpose.

As described above, the blow molding apparatus using the pressurized liquid according to the present invention can control the temperature of the liquid supplied into the preform with high accuracy without impairing the productivity. From the viewpoint of improving the quality of containers and improving productivity, it is expected that they will be widely used in the field of blow molding using pressurized liquid.

DESCRIPTION OF SYMBOLS 1; Metal mold | die 2; Cavity 4; Blow nozzle 5; Insertion cylinder piece 5a; Circumferential step part 6; Supply cylinder part 6a; Inlet path 6b; Discharge path 6c; Rod 9; seal pin 9 a; shaft body 9 t; seal cylinder piece 9 ta; taper edge 11; partition wall member 12; support rod piece 13; vent hole 21; Circulation path Fs; supply path Hs; head space L; liquid Ls: liquid level P1, P2, P3; pipe R1, R2; pipe S; space V1, V2, V3, V4; valve Vm; 32; Mouth tube portion 33; Neck ring 41; Container 101; Mold 103; Neck support collar 104; Blow nozzle 108; Rod 110; Guide tube portion 111; Insertion holes R101, R102, R103; ; Valve

Claims (4)

The blow mold (1) and the bottomed cylindrical preform (31) are fitted into the mold (1) and closely fitted to the mouth tube (32) of the preform (31). And a pressurized liquid supply part (22) is disposed, and the liquid (L) pressurized from the pressurized liquid supply part (22) is supplied to the blow nozzle (4). A blow molding device that supplies the preform (31) through the mold (1) and shapes the container (41) in an expanded state along the cavity of the mold (1),
A valve mechanism (Vm) is provided at the downstream end of the supply path (Fs) of the liquid (L) in the blow nozzle (4) so that the supply path (Fs) can be opened and closed, and the valve mechanism (Vm ) Can be circulated in the supply path (Fs) and pressurized liquid supply section (22) in the closed state, and pressurized into the preform (31) through the supply path (Fs) in the open state. Blow molding apparatus configured to be able to supply the liquid (L). The pressurized liquid supply unit (22) is provided with a liquid circulation unit (23) that supplies liquid (L) by adjusting to a predetermined temperature, and the supply path (Fs) is the supply path of the blow nozzle (4). Via the introduction path (6a) disposed at the upstream end of (Fs), the pressurized liquid supply part (22) is openably and closably connected, and the upstream end of the valve mechanism (Vm) is located at the downstream end. The fluid circulation part (23) is openably and closably communicated via a discharge path (6b) disposed in the valve mechanism (Vm) in a closed state via the liquid circulation part (23). The blow molding apparatus according to claim 1, wherein the liquid (L) can be circulated between the supply path (Fs) and the pressurized liquid supply section (22). A rod-like seal pin (9) is inserted and arranged in the blow nozzle (4) so as to be movable in the axial direction of the blow nozzle (4), and the tip of the seal pin (9) is disposed inside the blow nozzle (4). The supply path (Fs) can be closed by contact with the seal step (6s) disposed on the peripheral surface, and the seal pin (9s) is connected to the seal step (6s) at the tip of the seal pin (9). The blow molding apparatus according to claim 1 or 2, wherein the valve mechanism (Vm) is configured by contact and disengagement. The blow molding device according to claim 3, wherein the rod (8) is inserted into the cylindrical rod-shaped shaft (9a) so as to be slidable in a liquid-tight manner to form a seal pin (9).

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