CN100513136C - Stretch blow molding method for grippable bottle - Google Patents

Abstract

A stretch blow molding method for molding a grippable bottle with a holding recessed part at a body part without using special blow cavity dies, wherein a stretching rod (16) is inserted from the opening side of a preform (12), the blow cavity dies (10) and (10) with projected parts for molding the holding recessed part are moved to the preform (12) after a vertical axis stretching step for stretching the preform (12) in the vertical axis direction is started to complete the clamping of the blow cavity molds (10) and (10).

Description

Stretch Blow Molding Method for Holdable Bottles

technical field

The present invention relates to a stretch blow molding method of a synthetic resin container, and more particularly to a stretch blow molding method of a grippable bottle having a concave portion on the trunk of the container.

Background technique

The immediate motivation for the invention lies in containers for edible oils.

In Asian countries, the method of "selling by portion" is widely used for cooking oil. Consumers buy the desired portion at the store and pack the oil into a variety of containers to take away.

However, in recent years, edible oil filled in PET containers has been widely distributed and sold. From the perspective of hygiene and distribution costs, the advantages of this method are obvious.

In some regions, it is practiced to pour cooking oil directly into a pan placed on the fire. At this time, as a container that is easy to hold and pour, a container with a handle in which a handle formed separately from the container is integrated with the container is considered first. However, this type is generally not easy to shape, and the cost is easy to increase. Also, due to the material of the handle part, it is also not ideal from the standpoint of container recycling.

Based on these studies, the applicant considers that, among edible oil containers, a handleable bottle having a recessed portion for easy gripping on the trunk portion is promising. Considering the situation when housewives use it in the kitchen, the following design scheme has been studied: the width of the grip part is small, the concave part is deep, and the fingers are easy to catch.

However, it may be difficult to form a deep recess in the body of a PET container by conventional biaxial stretch blow molding.

The applicant has studied a similar subject in the forming of PET system lemonade beverage bottle before. The glass bulbs in the container are prevented from falling to the bottom by utilizing the recessed portion on the trunk of the lemon juice bottle that becomes thinner toward the inside of the trunk. The recessed portion of the body forms a very narrow space inside the container.

In recent years, such synthetic resin containers having recessed portions in the trunk tend to be converted to containers made of polyethylene terephthalate (hereinafter referred to as "PET") due to the need for recycling. In the past, as shown in FIG. 9, such a PET container 1 having a concave portion 6 on the trunk portion is inside a special blow molding die 10, 10 after mold clamping, and a bottomed cylindrical shape is formed by using an extension rod 16. The preform 12 of the preform 12 is carried out longitudinal axis extension, and utilizes the high-pressure blowing air to carry out the molding process that it is extended laterally, the concave part forming mold 13,13 is extruded toward the preform 12 side, thereby forms the concave part 6 (referring to utility model Registration No. 3074616).

With this stretch blow molding method, since the longitudinal axis stretching process and the high-pressure blow molding process are to be carried out in the state where the blow molding dies 10, 10 are clamped, it is necessary to have concave forming molds 13, 13 that can advance and retreat independently. . In order to drive the recess forming dies 13, 13 to advance and retreat independently, hydraulic cylinders 14, 14 and pistons 15, 15 for the recess forming dies 13, 13 are required, and a hydraulic circuit for operating them is also required.

Contents of the invention

It is an object of the present invention to provide a stretch blow molding method capable of molding a handleable bottle having a concave portion on the trunk without using a special blow die.

In order to achieve the above object, in one aspect of the present invention, a method for stretch blow molding of a grippable bottle having a concave portion on the trunk portion is characterized in that it includes: Inserting the extension rod to extend the preform along the longitudinal axis; mold clamping process, after the above-mentioned longitudinal axis extension process starts, the blow molding die is advanced relative to the above-mentioned preform to complete the die clamping of the blow molding die, The blow molding die has a convex portion for forming the above-mentioned concave portion; in the high-pressure blow molding process, after the above-mentioned mold clamping process is completed, high-pressure blow molding air is introduced into the above-mentioned preform.

According to this aspect of the present invention, the longitudinal axis stretching process is started before the mold clamping of the blow molding die is completed, so it is possible to form a flexible mold with a relatively large concave portion on the trunk without using a conventional complicated and expensive metal mold. Hold the bottle. In addition, the wall thickness distribution of the preform in the longitudinal axis direction can be easily adjusted by the longitudinal axis stretching process by means of the stretch rod.

Here, in the above-mentioned longitudinal-axis stretching step, low-pressure blowing air may be introduced at the same time as or after the start of the longitudinal-axis stretching drive of the above-mentioned stretch rod.

In this way, during the process of stretching the longitudinal axis of the preform, the stretching rod can be prevented from coming into contact with the inner surface of the preform.

Furthermore, the protrusion may be brought into contact with the surface of the preform after the longitudinal axis stretching by advancing the blow die after the completion of the longitudinal axis stretching step.

In this way, after adjusting the thickness distribution of the grippable bottle in the longitudinal direction by the longitudinal stretching process, the protrusions contact the surface of the preform, so that the protrusions do not interfere with the adjustment of the thickness distribution in the longitudinal direction. Furthermore, it is possible to prevent the surface of the preform from being scratched due to the contact between the preform and the convex portion during the extension of the longitudinal axis.

Description of drawings

Fig. 1 is a front view of a handleable bottle according to one embodiment of the present invention.

Fig. 2 is a right side view of a handle bottle according to an embodiment of the present invention.

Fig. 3 is a rear view of a handleable bottle according to an embodiment of the present invention.

Fig. 4 is a perspective view of a handleable bottle according to an embodiment of the present invention.

Fig. 5 is a view showing a state before stretch blow molding.

Fig. 6 is a view showing a longitudinal axis stretching step.

Fig. 7 is a diagram showing a mold clamping process and a high pressure blow molding process.

Fig. 8 is a view showing a state after stretch blow molding.

Fig. 9 is a view showing a conventional stretch blow molding process.

Detailed ways

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

1 to 8 are diagrams illustrating a stretch blow molding method according to an embodiment of the present invention. Fig. 1 is a front view of the handleable bottle 1, Fig. 2 is a right side view of the handleable bottle, Fig. 3 is a rear view of the handleable bottle, Fig. 4 is a perspective view of the handleable bottle, and Fig. 5 is a view before stretch blow molding Figure 6 is a diagram showing the longitudinal axis stretching process, Figure 7 is a diagram showing the mold clamping process and high pressure blow molding process, and Figure 8 is a diagram showing the state after stretch blow molding.

As shown in FIG. 1 , the synthetic resin, such as PET, handleable bottle 1 has an open neck 2 , a substantially cylindrical trunk 3 , and a bottom 4 having a dome-shaped raised bottom shown by a dotted line. The trunk portion 3 of the handleable bottle 1 has: a flat label sticking part 7, which is located on the front side of the handleable bottle 1, and is surrounded by shallow grooves; Recessed to the inside of the trunk part 3 ; a plurality of annular grooves 9 formed along the circumferential direction of the trunk part 3 .

The holding recesses 8, 8 are formed one on each of the left and right sides of the body part 3 in the middle section in the height direction in which the bottle 1 can be held. As shown in FIG. 3 , on the opposite side of the label attachment portion 7 on the trunk portion 3, that is, on the back side of the trunk portion 3, the wall portion of the trunk portion 3 sandwiched between the holding recesses 8 and 8 is formed as a gripping portion. 80. After holding things in the bottle 1, the buyer can put his thumb into one holding recess 8, put his remaining fingers in the other holding recess 8, and hold the holding portion 80 to carry the bottle 1. .

Hereinafter, the molding method of the grippable bottle 1 will be described in detail with reference to FIGS. 5 to 8 .

(input process)

FIG. 5 is a schematic view of the stretch blow molding die apparatus of the stretch blow molding unit 100, showing a state before start of stretch blow molding. In the stretch blow molding method of this embodiment, the bottomed cylindrical preform 12 having the open neck 2 is molded in advance by injection molding or compression molding using the preform molding section. The preform 12 is introduced into a heating unit (not shown) that is disposed integrally or integrally with the preform forming part. In the heating section, the preform 12 is heated to a temperature suitable for stretching, except the neck portion 2, by means of a heating mechanism such as a plurality of infrared heaters.

As shown in FIG. 5 , the preform 12 having reached a temperature suitable for stretching is supported by the conveying member 11 in an inverted state, and is carried into the blow molding unit 100 and stopped. In the blow molding part 100, there are: blow molding dies 10, 10, which are arranged on both sides of the preform 12, and are split molds in a mold-opening state; neck guides 20, 20, which are slidable It is arranged at the lower part of the blow molding dies 10 and 10; the bottom mold 18 is arranged above the preform.

The neck guides 20 , 20 consist of a pair of split molds holding the neck 2 of the preform 12 . It is driven together with the blow dies 10, 10 to advance and retreat relative to the preform 12, but is arranged to advance toward the preform side compared with the blow dies 10, 10 by means of an elastic member not shown ( The state of applying force) to a certain distance. Therefore, if the blow dies 10, 10 are advanced relative to the preform 12, the neck guides 20, 20 can hold the neck portion of the preform 12 before the blow dies 10, 10 are closed. 2.

Convex portions 21 , 21 are formed to protrude from the cavities of the blow dies 10 , 10 on the side facing the preform in order to form the gripping recesses 8 , 8 capable of gripping the bottle 1 . In order to facilitate the understanding of the forming process of the convex parts 21, 21 and the preform 12, Figs. 5-7 use the convex parts 21, 21 to represent the longitudinal sections of the blow molding dies 10, 10.

(Longitudinal axis stretching process)

Next, as shown in FIG. 6, the blow molding dies 10, 10 in the form of split molds are advanced to the side of the preform 12 together with the neck guides 20, 20, and are first held by the neck guides 20, 20 from both sides. Stop while holding neck 2. At this time, the blow dies 10, 10 are in the state before mold closing, and they are stopped with a distance of at least the convex parts 21, 21 formed on the blow dies 10, 10 out of contact. The outer surface of the preform 12 during longitudinal axis extension. Opening and closing of the blow dies 10 and 10 is performed by a not-shown clamping device such as a hydraulic device. The midway stop of the mold clamping action of such blow molding dies 10, 10 can be carried out in the following manner, that is, when the blow molding die is detected by a sensor arranged at the halfway stop position between the blow molding dies 10, 10 After mold 10, 10, make the solenoid valve of the hydraulic device inactive (Nu-Tral), thus stop the mold clamping action. In addition, in the case of performing a more precise stop operation, in addition to the above-mentioned sensors, an air cylinder or the like may be arranged at a predetermined position to perform a forced stop to stop the blow molds 10 , 10 halfway.

In addition, while the blow dies 10, 10 advance, the bottom mold 18 is lowered to a predetermined position shown in FIG. 6 and stopped.

Then, the extension rod 16 is driven to extend the longitudinal axis from below the conveying member 11, so that it pushes the inner side of the bottom of the preform 12 along the longitudinal axis and rises toward the bottom mold 18 side, so that the preform 12 moves vertically along the longitudinal axis. extend in the direction. When the preform 12 is extended in the longitudinal direction, the trunk portion of the preform 12 becomes thinner, and low-pressure primary blowing air is introduced into the inside of the preform 12 so as not to contact the extension rod 16 . This prevents galling of the inner surface of the preform 12 during the longitudinal axis stretching process. At this time, the neck guides 20 and 20 hold the neck 2 from both sides, so even if the extension rod 16 is driven to extend the longitudinal axis, the preform 12 will not float from the conveying member 11 .

The pressure of the low-pressure primary blowing air is such that the preform 12 does not touch the extension rod 16 , for example, it may be 1.0 MPa. In addition, the low-pressure primary blow air may be introduced at the same time as the start of the longitudinal axis extension drive of the extension rod 16, or may be introduced a little later than that. In addition, the low-pressure primary blowing air may be introduced for a certain period of time or a certain amount, and then the introduction of the gas may be stopped by closing an air valve not shown, or intermittent blowing may be performed in which the air is introduced again after a predetermined period of time.

Alternatively, the longitudinal extension drive of the extension rod 16 may start at the moment when the neck 2 is held by the neck guides 20 , 20 . As long as the neck guides 20 , 20 hold the neck 2 , depending on the longitudinal extension of the preform 12 , the blow molding dies 10 , 10 can thus also be advanced without stopping.

(mold clamping process and high pressure blow molding process)

Furthermore, as shown in FIG. 7 , after the longitudinal axis extension drive of the extension rod 16 is completed, the blow molding dies 10 and 10 are driven to advance each other to perform mold clamping until the two are in close contact, and then the pressure is increased to complete the mold clamping process . The high-pressure blow molding process refers to that after the mold clamping of the blow molding dies 10 and 10 is completed, high-pressure secondary blow molding air such as 2.0 MPa air is introduced, and by pressing on the cavity surfaces of the blow molding dies 10 and 10 Shaped from above, the trunk portion 3 and the bottom portion 4 including the holding recesses 8 and 8 of the grippable bottle 1 of the final shape are formed.

The longitudinal axis extension of the preform 12 by the extension rod 16 can adjust the wall thickness distribution of the final molded product, that is, the handle bottle 1 in the direction of the longitudinal axis. Therefore, by closing the blow dies 10, 10 after the preform longitudinal axis stretching process is completed, adjustment can be made without affecting the wall thickness distribution in the longitudinal axis direction of the grippable bottle 1 . This is because: by making the protrusions 21, 21 used for holding the recesses formed on the blow molding dies 10, 10 contact the trunk portion of the preform 12 extended on the longitudinal axis, the parts where the protrusions 21, 21 contact The extension of the lifting part (upper part in Fig. 7) in the longitudinal direction is substantially stopped.

Furthermore, even before the longitudinal axis stretching step of the preform is completed, the mold clamping drive of the blow dies 10, 10 can be started. In this case, the mold closing drive timing of the blow dies 10, 10 is adjusted so that the protrusions 21, 21 formed on the blow dies 10, 10 do not come into contact with the predetermined portion in the middle of the longitudinal axis extension. The sides of the blank 12 are formed. In order to avoid such delicate action adjustments, it is preferable to make the blow molding dies 10, 10 as close as possible to the preform 12 within the range where the convex parts 21, 21 formed on the blow molding dies 10, 10 do not touch the preform 12. The formed blank 12 is on standby.

Also, when the ground portion of the bottom 4 has an acute-angled pressure-resistant shape, so-called champagne bottom molding in which the bottom mold 18 is closed later than the blow dies 10 and 10 can be performed.

After the mold clamping of the blow molding dies 10, 10 and the bottom mold 18 is completed, high-pressure secondary blowing air is introduced, and then, within a predetermined time, for example, about one second, the bottle can be held by the secondary blowing air. 1 The state of being pressed against the blow dies 10, 10.

(Output process)

Then, as shown in FIG. 8 , the high-pressure air capable of gripping the inside of the bottle 1 is discharged, the bottom mold 18 is raised, and the blow molding dies 10, 10 are retracted to open the mold. In this way, the handleable bottle 1 is formed, and the trunk portion 3 has the holding recesses 8, 8 which are recessed deeply inward. The bottle 1 can be grasped and delivered from the blow molding unit 100 in a state supported by the transport member 11, and then transported to a bottle discharge unit (not shown) to be taken out of the blow molding machine.

In this way, at the moment when the longitudinal axis extension starts, the blow molding dies 10 and 10 having the convex portion 21 are in the state before closing the mold, and it is set to have a sufficient preform longitudinal direction between the preform 12 and the convex portion 21. The state of the axial extension space, whereby the extension of the longitudinal axis of the preform 12 is not hindered by the protrusion 21, can obtain a container with a uniform wall thickness distribution as a whole.

In addition, the present invention is not limited to the present embodiment, and various modifications are possible within the scope of the gist of the present invention.

For example, it is also possible to use intermediate blowing air whose pressure is set to the intermediate pressure of the primary blowing air and the secondary blowing air. In this case, the intermediate blowing air starts to blow in when the convex parts 21, 21 of the blow molding dies 10, 10 are about to come into contact with the surface of the preform 12 in the middle of the extension of the preform's longitudinal axis, Scuffing caused by the protrusions 21 , 21 can thus also be reduced.

In addition, in the present embodiment, the blow molding apparatus that supports and conveys the preform 12 via the conveyance member 11 has been described, but it can also be applied to an injection stretch blow molding apparatus that The apparatus is transported while holding the neck 2 by the lip die from the injection molding process of the preform 12 to the stretch blow molding process. In this case, since the neck portion 2 is always held during the forming process, the preform 12 can be reliably held even when the extension rod 16 is driven to extend the longitudinal axis.

Claims (4)

1. A stretch blow molding method for a handleable bottle having an open neck and a bottomed cylindrical body portion, the body portion having a recess for holding, characterized in that: include: In the longitudinal axis stretching process, in the state before closing the blow molding die, an extension rod is inserted from the opening side of the preform to extend the preform in the longitudinal direction. The blow die integrally has a For the convex part forming the above-mentioned holding concave part; In the mold clamping process, after the above-mentioned longitudinal axis extending process starts, the blow molding die is advanced relative to the above-mentioned preform, and the mold clamping of the blow molding die is completed; In the high-pressure blow molding process, after the above mold clamping process is completed, high-pressure blow molding air is introduced into the above-mentioned preform. 2. The stretch blow molding method of a grippable bottle according to claim 1, wherein in the longitudinal stretching step, low-pressure blow air is introduced at the same time as or after the longitudinal stretching drive of the stretch rod is started. 3. The stretch blow molding method of a grippable bottle according to claim 1 or 2, characterized in that, after the above-mentioned longitudinal axis stretching process is completed, the above-mentioned convex part and the longitudinal axis are stretched by advancing the above-mentioned blow molding die. After the surface contact of the above preform. 4. The stretch blow molding method of a handleable bottle according to claim 1 or 2, characterized in that it comprises: The step of advancing the blow molding die to a standby position where the protrusions approach the preform before longitudinal stretching, before starting the longitudinal stretching step; and A step of further advancing the blow die from the standby position after starting the longitudinal stretching step, and bringing the protrusions into contact with the surface of the longitudinally stretched preform after the longitudinal stretching step is completed.

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