JP2003181907A - Method and device of biaxial orientation blow molding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of biaxial orientation blow molding allowed to obtain a container with excellent wall thickness distribution and with high- quality even when the center of a neck part is eccentric to the central axis of a container body. <P>SOLUTION: In this method, a preform 14 is formed into the container 16 by biaxial orientation blow molding. The method comprises the steps of moving a stretching rod 20 along the axis of the preform 14 and moving the stretching rod 20 with an inclination to the axis of the preform 14. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biaxial stretch blow molding method and apparatus for longitudinally stretching a preform by using a stretching rod and blow molding it into a container.

[0002]

BACKGROUND ART AND PROBLEMS TO BE SOLVED BY THE INVENTION In general,
Containers made of synthetic resin such as polyethylene terephthalate (PET) are known.

Such a container made of synthetic resin is usually formed by injection-molding a bottomed tubular preform by biaxial stretch blow molding and using a stretch rod and blow air to stretch it in the longitudinal and transverse directions. Manufactured.

In many preforms used for molding such containers, the central axis of the neck portion and the central axis of the preform basically coincide with each other.

By the way, in such a container, the center axis of the neck portion including the opening is usually aligned with the center axis of the container body, and if it is stretched along the center axis of the container body by a stretching rod, A product with a good wall thickness distribution can be obtained.

However, in the case of a container in which the central axis of the neck portion is eccentric with respect to the central axis of the container body or the central axis of the container bottom portion, when the stretching rod is stretched at the center position of the neck portion, The tip does not come into contact with the center of the bottom, and the thickness distribution is uneven, which makes it difficult to obtain a container of good quality.

An object of the present invention is to obtain a good quality container having a good wall thickness distribution even when the center axis of the neck portion is eccentric with respect to the center axis of the container body or the center of the container bottom. It is an object of the present invention to provide a biaxial stretch blow molding method and apparatus that can be used.

[0008]

In order to achieve the above object, the biaxially stretch blow molding method of the present invention is a method for biaxially stretch blow molding a preform into a container, in which a stretch rod is provided with an axis of the preform. Moving along,
And a step of moving the stretching rod while inclining with respect to the axis of the preform.

According to the present invention, since there is a step of moving the stretching rod along the axis of the preform, and a step of moving the stretching rod while inclining with respect to the axis of the preform, the axis of the preform is It is possible to obtain not only the wall thickness distribution along but also the wall thickness distribution along the inclined direction of the stretch rod.

For example, even in an eccentric container in which the center of the container bottom does not exist on the preform axis (or the neck axis), the inclined stretch rod moves toward the center of the container bottom, A uniform and desirable thickness distribution can be obtained even near the bottom.

In the present invention, in the step of moving the stretching rod along the axis of the preform, the stretching rod is moved until the tip of the stretching rod at least comes into contact with the bottom of the preform, and the tip of the stretching rod is moved. The drawing rod can be moved while being inclined with respect to the axis of the preform while being in contact with the bottom of the preform.

With this structure, the bottom of the preform is surely guided to the intended position by inclining and moving the stretch rod with the tip of the stretch rod in contact with the bottom of the preform. It is possible to obtain a product having a better wall thickness distribution.

In the present invention, in the step of inclining and moving the stretching rod, the tip of the stretching rod can be moved toward the center of the bottom of the container body.

With such a construction, the tip of the stretching rod is slanted and moved toward the center of the bottom of the container body to bring the bottom of the preform into contact with the center of the bottom of the container body, It is possible to obtain a product with a better wall thickness distribution and good quality.

The biaxial stretch blow molding apparatus of the present invention is a biaxial stretch blow molding apparatus for biaxially stretch blow molding a preform into a container, wherein a stretching rod for vertical axis stretching is a stretching rod of a stretching rod lifting mechanism. An engaging means for slidably engaging the fixed plate and a tilting means for tilting a guide portion for guiding the stretching rod by a tilting driving means are provided, and the stretching rod is tilted by a predetermined angle and moved. The feature is that it has been made possible.

According to the present invention, the extending rod is slidably engaged with the extending rod fixing plate of the extending and lowering mechanism by the engaging means, and the guide portion of the extending rod is inclinable by the inclining means. For example, the stretching rod can be moved along the axis of the preform at the start of stretching, and the stretching rod can be tilted and moved during stretching on the vertical axis,
Even when the center axis of the neck portion is eccentric with respect to the center axis of the container body or the center of the container bottom, it is possible to obtain a container of good quality in which the thickness distribution is less likely to be biased.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

1 to 8 are views showing a biaxial stretch blow molding apparatus for an eccentric neck portion container according to an embodiment of the present invention.

This biaxial stretching blow molding apparatus 10 is shown in FIG.
As shown in FIG. 2, the preform 14 held in an inverted state on the conveying member 12 is blow-molded into the shape of the neck eccentric container 16, and the stretching rod 20 is moved up and down with respect to the blow cavity mold 18. The drawing rod elevating mechanism 22 is provided.

The preform 14 is, as shown in FIG.
It has a bottomed tubular shape having a neck portion 24, a body portion 26, and a bottom portion 28.

As shown in FIG. 4, the neck portion eccentric container 16 has a neck portion 24 and a container body 36 composed of a shoulder portion 30, a body portion 32 and a bottom portion 34.
The center position 38 is eccentric by the distance L with respect to the center 40 of the container bottom 34.

The blow cavity mold 18 is shown in FIGS.
As shown in FIG. 5, the mold is composed of split molds, and can be opened and closed and clamped on the machine base 45 along the tie rods 42 by a blow mold clamping device (not shown).

In FIG. 2, the left blow cavity mold 18 is shown in a mold closed state and the right blow cavity mold 18 is shown in a mold open state, and the cross section of the right blow cavity mold 18 is omitted.

Although not shown, a bottom mold is combined with the upper part of the blow cavity mold 18.

Further, the blow cavity mold 18 has two cavity faces 44 forming the container side face in a state where the neck portion eccentric container 16 is inverted, and a split mold is provided at the lower end of each cavity face 44. A constructed neck support 46 is attached.

Then, the neck portion 24 of the preform 14 conveyed by the conveying member 12 is sandwiched by the neck support 46.

As shown in FIG. 1, the carrying member 12 is engaged with the carrying rail 48 and also with the carrying chain 50 wound around a carrying sprocket (not shown).
A fixed portion 52 that is movable by driving the transport chain 50, and is attached by penetrating the fixed portion 52,
An upper end portion is inserted into the neck portion 24 of the preform 14 and has a cylindrical mounting table 54 that supports the preform 14 in an inverted state.

A seal piston 56 is provided below the conveying member 12 stopped at the blow molding position as a guide member for penetrating the stretching rod 20 and guiding the stretching rod 20 when moving up and down. .

This seal piston 56 is shown in FIGS.
As shown in FIG. 5, the piston 57 is provided so that it can be moved up and down by driving air, and the seal portion 96 at the upper end is brought into contact with the lower end of the mounting table 54 for sealing, and the air formed inside at the time of blow molding is also formed. Blow cavity mold 1 from supply path 63
Blow air can be supplied to the inside of the unit 8.

The contact surface of the seal portion 96 is spherical.

The stretching rod elevating mechanism 22 fixes a rising cylinder fixing plate 60 to the lower ends of a plurality of, for example, four guide rods 58 suspended from the machine base 45, and a pair of lower surface side of the rising cylinder fixing plate 60. The ascending cylinder 62 is fixed.

Further, the machine base 45 and the lifting cylinder fixing plate 60
The guide rod 58 between the drawing cylinder fixing plate 6 and
4 and a stretch rod fixing plate 66 are provided so as to be able to move up and down.

A stretching cylinder 68 is fixed to the lower surface side of the stretching cylinder fixing plate 66, and a cylinder rod 70 of the ascending cylinder 62 is attached to the stretching cylinder fixing plate 64.
Are connected.

The extension rod fixing plate 66 is connected to the cylinder rod 72 of the extension cylinder 68 on the lower surface side and to the lower end portion of the extension rod 20 on the upper surface side.

A stopper rod 74 for restricting the upper limit position of the stretching cylinder fixing plate 64 is fixed to the stretching cylinder fixing plate 64 by penetrating the rising cylinder fixing plate 60.

Further, a stopper rod 75 for restricting the upper limit position of the stretching rod fixing plate 66 is fixed to the stretching rod fixing plate 66 by penetrating the stretching cylinder fixing plate 64.

Further, the lower end of the stretching rod 20 is placed at a lower end of the stretching rod 20 so that the stretching rod 20 is in a state of being perpendicular to the stretching rod fixing plate 66 and can be tilted with respect to the vertical direction. And the engaging means 76.

The engaging means 76 is attached to the U-shaped rolling rail 80 mounted on the upper surface of the stretching rod fixing plate 66 and the lower end of the stretching rod 20 so that the engaging means 76 can roll inside the rolling rail 80. The cam follower 82 and the cam follower 82 roll in the rolling rail 80 so that the stretching rod 20 can be inclined with respect to the vertical direction of the stretching rod fixing plate 66.

As shown in FIGS. 4, 6 and 7, the extending rod 20 has the tilting means 7 for tilting the seal piston as a guide member.
By tilting by 8 the cam follower 82 of the engaging means 76 of the stretch rod 20 rolls in the rolling rail 80 of the stretch rod fixing plate 66 and can be inclined with respect to the axis of the preform.

As shown in FIGS. 5 to 8, the tilting means 78 is provided with the seal piston 56 rotatably around the rotary shaft 84 in the vicinity of the upper part of the seal piston 56. The tilt cylinder 86 is connected by a link arm 88.

By moving the cylinder rod 90 of the tilting cylinder 86 forward and backward, the stretching rod 20 can be moved along the axis of the preform 14 or the stretching rod 20 can be moved obliquely. You can do it.

The tilting cylinder 86 is rotatably attached to the attachment member 92 attached to the machine base 45 via the pin 94 so that the movement in the rotational direction during driving can be absorbed.

Further, even if the seal piston 56 is tilted or not tilted, the contact surface of the seal portion 96 is spherical, so that the sealability with the mounting table 54 is always secured.

Next, a biaxial stretch blow molding method for a neck portion eccentric container using such a biaxial stretch blow molding apparatus 10 will be described with reference to FIGS.

The blow cavity mold and the like are omitted in FIGS.

First, as shown in FIG. 5, the lifting cylinder 6
2 and the stretching cylinder 68, the stretching cylinder fixing plate 6
4 and the extension rod fixing plate 66 are lowered to extend the extension rod 2
0 is lowered and the stretching rod 20 is moved to the conveying member 1
The preform 14 is transported by the transport member 12 in a state of being retracted from the transport position by 2.

Next, as shown in FIG. 6, with the preform 14 being conveyed to the molding position by the conveying member 12, the raising cylinder 62 is driven to move the stretching cylinder fixing plate 64 and the stretching rod fixing plate 66. The stopper rod 74 raises the rod 20 until it stops, and the stretching rod 20 is moved along the axis of the preform 14 at the start of the longitudinal stretching.

In this state, the tip end of the drawing rod 20 comes into contact with the bottom portion 28 of the preform 14 and is slightly, for example, 6 mm.
Stretch to some extent.

Next, as shown in FIG.
When the link arm 88 is pressed by the tilting cylinder 86 after the tip of the contacting the bottom part 28 of the preform 14, the seal piston 56 tilts around the rotation shaft 84 and the cam follower 82 provided at the lower end of the stretching rod 20 moves. Rolling along the rolling rail 80, the extension rod 20
Becomes a slanted state, and the bottom portion 28 of the preform 14 slightly moves accordingly.

Next, from the state of FIG. 7, as shown in FIG. 8, the seal piston 56 is raised to bring the seal portion 96 into contact with the lower end surface of the mounting table 54 of the conveying member 12, and the stretching cylinder 68 fixes the stretching cylinder 68. The plate 64 is raised by the stopper rod 75 until it stops.

As a result, the stretching rod 20 is moved in an oblique state during the vertical axis stretching, and the preform 14 is obliquely stretched in this state.

When the preform 14 is longitudinally stretched by the stretching rod 20, blow air is supplied from the seal piston 56 into the blow cavity mold 18, specifically, the preform 14 so that the preform 14 is moved in the horizontal axis direction. Blow mold.

Further, in the step of moving the stretching rod 20 obliquely, by moving the tip of the stretching rod 20 toward the center of the bottom portion 34 of the container body 36, uneven distribution of the wall thickness can be further prevented, which is favorable. You can get various quality products.

After the blow molding is completed, as shown in FIG. 7, the stretching cylinder 62 and the stretching cylinder 68 lower the stretching cylinder fixing plate 64 and the stretching rod fixing plate 66 to convey the stretching rod 20 to the conveying member 12. It is retracted from the position and waits for the next conveyance member 12.

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

For example, in the above-described embodiment, the case where the preform is subjected to the biaxial stretch blow molding in the inverted state has been described, but the present invention is not limited to this example, and the present invention is also applied to the case where the preform is blow-molded. It is possible.

Further, in the above-mentioned embodiment, after the tip of the drawing rod comes into contact with the bottom of the preform, the drawing rod is slanted and moved. However, the present invention is not limited to this example, and It is also possible to move the stretching rod at an angle before contacting the bottom of the preform or while the stretching rod is stretching the preform.

Furthermore, in the above-mentioned embodiment, the tip of the stretching rod is moved toward the center of the bottom of the container body. However, it is not always necessary to move it toward the center of the bottom, and the thickness of the container body is not limited to this. The moving direction can be appropriately selected as long as the distribution is good.

Furthermore, the stretching rod elevating mechanism does not have to elevate and lower in two steps, but may use a driving means such as a single stretching cylinder or an electric motor.

In this case, it is desirable to control so as to incline at an arbitrary position, such as monitoring the position of the stretching cylinder.

[Brief description of drawings]

FIG. 1 is a partial front view showing a biaxial stretch blow molding device for an eccentric neck portion container according to an embodiment of the present invention.

2 is a side view of the biaxial stretch blow molding apparatus of FIG. 1. FIG.

FIG. 3 is a sectional view showing a state before the seal piston is tilted.

FIG. 4 is a cross-sectional view showing a state where the seal piston is tilted from the state shown in FIG.

FIG. 5 is a front view showing a biaxial stretch blow molding method for the neck eccentric container according to the embodiment of the present invention before the start of stretching.

FIG. 6 is a front view showing a state where stretching is started from the state of FIG.

FIG. 7 is a front view showing a state in which the stretch rod is slanted from the state of FIG.

FIG. 8 is a front view showing a state where the stretching rod is moved while being inclined from the state of FIG.

[Explanation of symbols]

10 Biaxial stretch blow molding machine 14 Preform 16 Neck eccentric container 20 Stretching rod 22 Stretching rod lifting mechanism 24 neck 28 Bottom of preform 34 Bottom of container body 36 container body 38 Center position of neck 40 Center axis of container body 56 seal piston 76 Engaging means 78 Leaning means 86 tilting cylinder

Claims (4)

[Claims] 1. A method of biaxially stretch blow molding a preform into a container, comprising the steps of moving a stretch rod along an axis of the preform, and inclining the stretch rod with respect to the axis of the preform. And a step of moving the biaxially stretched blow molding method. 2. The stretching rod according to claim 1, wherein the step of moving the stretching rod along the axis of the preform moves the stretching rod until at least a tip of the stretching rod contacts a bottom portion of the preform. A biaxial stretch blow-molding method, wherein the stretch rod is moved while being inclined with respect to the axis of the preform in a state where the tip of the stretch contact the bottom of the preform. 3. The biaxial stretching blow according to claim 1 or 2, wherein in the step of tilting and moving the stretching rod, the tip of the stretching rod is moved toward the center of the bottom of the container body. Molding method. 4. A biaxial stretching blow molding device for biaxially stretching blow molding a preform into a container, wherein a stretching rod for longitudinal stretching is slidably attached to a stretching rod fixing plate of a stretching rod lifting mechanism. And a tilting means for tilting a guide part for guiding the stretching rod by a tilting driving means, wherein the stretching rod is movable at a predetermined angle. Axial stretch blow molding equipment.