JP2902119B2 - Preform injection molding method and apparatus - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a preform injection molding method and apparatus capable of shortening an injection molding cycle time while securing a sufficient cooling time.

BACKGROUND ART Injection shaping of a preform requires at least an injection cavity mold that defines an outer wall of the preform and an injection core mold that defines an inner wall of the preform. Furthermore, it is necessary to cool the preform to a temperature at which the preform can be released while maintaining the mold clamping state after the injection cavity mold and the injection core mold are mold-clamped and the preform is injection-molded.

In the past, since the mold release temperature of the preform had to be sufficiently lowered, the injection molding cycle time was increased and the production efficiency was deteriorated. The factors that increase the cooling time are as follows (1) to (4).

(1) For example, when the injection cavity mold and the injection core mold are released from the preform and the preform is dropped and taken out, the preform is not sufficiently deformed even if it comes into contact with other members. It is necessary to cool the preform to a low demolding temperature.

(2) When the release temperature of the preform is high, when the injection core mold is released from the preform, the preform comes into close contact with the core mold, and a release defect called so-called winding occurs.

(3) If the mold release temperature of the preform is high, there is no member that regulates the deformation of the preform after the mold is released from the injection core mold. Can not take out the preform.

(4) Insufficient cooling by the injection core mold causes crystallization especially on the inner wall of the preform due to insufficient cooling, and a preform having an opaque body is taken out.

In contrast, Japanese Patent Publication No. 4-15721 and Japanese Patent Laid-Open Publication No.
9, at each stop position of the intermittent rotation transfer means, injection molding section,
A rotary injection molding apparatus is disclosed in which a cooling unit and a take-out unit are sequentially arranged, and a preform molded in an injection molding unit is held in a neck mold of an intermittent rotation transfer unit, and is sequentially conveyed to a cooling unit and a take-out unit. ing.

According to this rotary injection molding apparatus, the above-mentioned (1)
It is not necessary to take into account the above-mentioned personnel, but the injection cycle time must be similarly lengthened due to the factors (2) to (4).

In addition, in the case of this rotary injection molding apparatus, a cooling pot and a cooling core are required in the cooling section, and a separate take-out station needs to be arranged. Cost. As described above, the rotary injection molding apparatus has caused an increase in the size and complexity of the apparatus and an increase in the number of members.

In addition, according to this rotary injection molding apparatus, in order to prevent crystallization of the neck portion having the largest thickness in the preform, the neck portion can be cooled by the neck mold. However, since the rotation direction is one direction, a rotary joint or the like is required to guide the refrigerant to the rotating neck type, and the configuration is complicated.

Further, in the conventional injection molding apparatus, the preform cannot be taken out unless the injection core mold is completely pulled out from the preform, and the rotary injection molding apparatus cannot transport the preform from the injection molding section to the next process. . When the injection core mold is completely pulled out from the preform in this way, there is a problem that the drawing stroke becomes longer and the overall height of the device becomes higher.

In addition, the preform is taken out before it is completely cooled by the injection core and the injection cavity (a state in which the preform has a temperature that can be processed in the next step), and the secondary processing such as blow molding is performed in the subsequent steps. When applying, there were the following problems.

(A) If the internal pressure (injection holding pressure) is not increased, sink occurs on the injection cavity side of the preform, and a preform having a uniform temperature cannot be obtained. Therefore, when this preform is blow molded, a molded product having a uniform thickness distribution cannot be obtained.

(B) When the internal pressure (injection holding pressure) is increased, a pressure difference occurs between the gate portion and the preform end portion (for example, the neck portion), resulting in a preform having a large residual stress at the preform bottom side where the pressure is high. Therefore, when the blow molding is performed, a molded product having a uniform thickness distribution cannot be obtained.

(C) When the preform is cooled in the injection core and the injection cavity, the preform shrinks as the cooling proceeds, and is in a direction away from the injection cavity surface. For this reason, there are portions on the outer peripheral wall surface of the preform that are not in contact with the portions that are in contact with the injection cavity, resulting in a difference in the cooling speed of the preform, resulting in an uneven temperature. Therefore, when this preform is blow-molded, a molded product having a uniform thickness cannot be obtained.

Accordingly, it is an object of the present invention to provide a preform injection molding method and apparatus capable of shortening the injection molding cycle time and improving production efficiency while sufficiently securing the preform cooling time. It is in.

It is another object of the present invention to provide a method and an apparatus for injection molding a preform which can prevent winding, uneven temperature or deformation by an injection core mold even when the preform release temperature is increased.

Still another object of the present invention is to provide a preform injection molding method and apparatus which can prevent whitening and crystallization due to insufficient cooling while shortening the injection molding cycle.

Still another object of the present invention is to mold a preform having a small residual stress without significantly increasing the injection holding pressure during the injection molding of the preform, thereby reducing the dependence of cooling by the injection cavity mold even if sink occurs. Accordingly, it is an object of the present invention to provide a preform injection molding method and apparatus which can reduce temperature unevenness of a preform at the time of taking out.

[Disclosure of the Invention] The method of the present invention comprises the steps of: clamping an injection cavity mold and an injection core mold each having a cooling unit at an injection molding station to injection mold a preform; Releasing the injection cavity mold from the preform, transferring the preform to a cooling / unloading station while cooling the preform with the injection core mold, and performing injection molding of the next preform at the injection molding station. A step of cooling the preform by the injection core mold at the cooling / unloading station until the end, and thereafter removing the preform from the injection core mold.

According to the method of the present invention, only the injection cavity mold is released from the preform after the preform injection molded in the injection molding station is cooled by the injection cavity mold and the injection core mold. Thereafter, the preform is transported to a cooling / unloading station by an injection core mold.
During the transportation and at the cooling / unloading station, after the preform is cooled by the injection core mold, the preform is unloaded.

Therefore, even after the injection cavity mold is released from the injection molding station, cooling by the injection core mold ensures a sufficient cooling time for the preform. Therefore, the release temperature of the preform when releasing the injection cavity mold at the injection molding station can be increased, and the injection molding cycle time is shortened. Even when the injection cavity mold is released at a high temperature, the deformation of the preform can be prevented by the injection core mold, and the crystallization and opacity of the body due to insufficient cooling can be prevented.

In the injection molding step, the preform having a neck portion having a portion that becomes an intercut in a mold opening direction can be injection-molded using a neck cavity mold that defines an outer wall of the neck portion. This neck cavity mold is composed of a pair of split molds having a cooling part.

When a neck cavity mold is used, in the transporting step and the cooling step at the cooling / unloading station, the preform is cooled while maintaining the injection core mold and the neck cavity mold in a mold-clamped state. Also,
In the unloading step at the cooling and unloading station, the injection core mold is necked by an amount of stroke sufficient to create a gap between the preform inner wall held by the neck cavity mold and the injection core mold. The cavity mold is relatively driven for release. Then, after that, the pair of split dies of the neck cavity type are opened and driven to take out the preform.

In this case, the neck portion of the preform can be continuously cooled by the neck cavity mold even after the release of the injection core mold, and the thick neck portion can be sufficiently cooled to prevent whitening and crystallization of the portion. Furthermore, since it is not necessary to pull out the injection core mold by the entire length of the preform, the release stroke of the injection core mold can be shortened.

Further, even after the release of the injection core mold, the injection core mold remains in the preform. Therefore, even if the preform is in close contact with one of the pair of split dies that constitute the neck cavity mold, the injection core mold does not. Movement of the preform in the opening drive direction of the split mold can be restricted.

The adjustment of the cooling time of the preform can be performed by adjusting the timing of the release driving of the injection core type at the cooling / unloading station. Therefore, the optimal cooling time of the preform can be set without necessarily changing the injection molding cycle time. Further, by adjusting the release timing of the injection core mold, it is possible to cope with an increase in the release force accompanying the progress of cooling of the preform, and the versatility of the injection molding apparatus is improved.

In the injection molding station and the cooling / unloading station 180 degrees apart by a rotation angle, the injection core mold and the neck cavity mold are both reversibly rotated, and the injection core mold and the neck cavity mold are rotated in both stations. It is preferable to exchange and transport.

This is because the reversible rotation of the interchanged transfer to each station of the injection core type and the neck cavity type each time facilitates connection of the refrigerant circulation pipe to the injection core type or the neck cavity type.

At the time of the transfer step and the cooling at the cooling / unloading station, the neck cavity mold is brought into close contact with the injection core mold by a return spring, and the molds are maintained in a mold-clamped state. By maintaining the tightened state, cooling of the preform can be promoted.

In this case, at the cooling / unloading station, the neck cavity mold holding the preform is separated from the injection core mold by an external force against the urging force of the return spring, and the injection core mold is separated from the preform by the preform. Release more.

In the releasing step of the injection cavity mold, a skin layer capable of maintaining the outer shape of the preform even after releasing the injection cavity mold is formed on an outer surface of the injection preform cooled by the injection cavity mold. It is preferable to do it later. This is because the injection molding cycle time can be set to the shortest while preventing deformation of the preform after release of the injection cavity mold.

When there is no undercut in the neck portion and it is not necessary to use the neck cavity mold, the step of taking out the preform at the cooling / unloading station discharges air from the injection core mold into the preform. Just do it.

The blow molding method according to the present invention includes the steps of: transporting the preform injection-molded as described above to a blow molding station while retaining heat at the time of the injection molding; and Placing the preform in a blow cavity mold, and blow molding a hollow body from the preform by driving the stretching rod longitudinally and introducing air from the blow core mold.

If the preform is released from the injection mold and subjected to secondary processing such as blow molding before it is completely cooled, the preform is released from the injection cavity relatively early, and Since the injection core is further uniformly cooled from the inside by the injection core whose adhesion is further improved by the shrinkage deformation, the quality, particularly the wall thickness distribution, of the molded article subjected to secondary processing such as blow molding is remarkably improved.

An injection molding apparatus for a preform according to the present invention is an injection molding apparatus for a preform, comprising: an injection molding station for injection molding the preform; and a cooling / unloading station for releasing the preform after releasing it after cooling. An injection core mold disposed at a position corresponding to each of the two stations and having a cooling function of the preform; a replacement transporting means for replacing and transporting the injection core mold to the two stations; The injection core mold and the injection cavity mold having a cooling function of a preform, which are arranged in the injection core mold, The mold molding drive of the injection core mold and the injection cavity mold in the injection molding station, and the preform Mold clamping means for relatively releasing the injection cavity mold from the mold; After the preform is placed in the station has been cooled by the injection core mold, characterized by having a a removal drive means for taking out driving said preform from said injection core mold.

With this apparatus, the method of the present invention described above is carried out, and a sufficient cooling time for the preform can be ensured while shortening the injection molding cycle time.

It is preferable that the exchange conveying means is constituted by a rotating disk that intermittently conveys the injection core mold to the injection molding station and the cooling / unloading station provided at positions separated by a rotation angle of 180 °.

Also in the device of the present invention, a neck cavity type can be used. In this case, a neck cavity mold that is relatively closed and opened with respect to the injection core mold is supported by the rotating disk. Also, this neck cavity type
The preform includes a pair of split dies that define an outer wall of a neck portion of the preform. Each of the pair of split dies has a cooling unit.

In this case, the turntable conveys the injection-molded preform to the cooling / unloading station while cooling the preform by the neck cavity mold and the injection core mold.

When a neck cavity mold is used as described above, the take-out driving means performs the injection by an amount of stroke sufficient to create a gap between the inner wall of the preform held by the neck cavity mold and the injection core mold. Releasing drive means for releasing the neck cavity mold relative to the core mold; and after releasing the neck cavity mold relative to the core mold, the pair of split dies are opened and the preform is taken out. And a split mold opening means.

In order to maintain the injection core mold and the injection cavity mold in the mold clamped state during transportation and the like, a return spring that urges the neck cavity mold toward the injection core mold and maintains both molds in the mold clamped state is provided. Used. At this time, the release driving means resists the urging force of the return spring,
The neck cavity mold is driven to release relative to the injection core mold.

As a structure for maintaining the neck cavity mold, two split plates respectively supporting the pair of split words constituting the neck cavity mold, and the two split plates are guided and supported so as to be able to come and go, and the return spring is provided. A guide member connected thereto, a pressing plate disposed on the two split plates, and a cover having a length that is set upright on the pressing plate and whose upper end does not reach the rotary plate. And a drive shaft.

At this time, the release driving means includes: a through hole provided in the rotary disk at a position facing the driven shaft; a drive shaft having a lower end above the through hole; And a first driving unit that is driven dynamically.

By the driving of the first drive unit, the lower end of the drive shaft protruding downward through the through hole of the turntable pushes the driven shaft, and the neck cavity mold is moved by the return spring. The injection core is driven to separate from the injection core mold against the urging force.

As a configuration for opening and driving the pair of split dies constituting the neck cavity mold, the two split plates have notches in which opposing ends thereof are cut out in a wedge shape. An elevating plate that moves up and down together with the drive shaft by a driving force may be provided.

Further, the split mold opening drive means is adapted to be driven by the second drive unit mounted on the elevating plate and lowered by the second drive unit to the notch formed in the two split plates. And a cam plate having a wedge-shaped tip.

With this configuration, the cam plate is driven downward by the second drive unit after the lifting plate is processed for the release driving of the injection core die, so that the downward stroke of the cam plate can be shortened.

It is preferable that the rotary plate on which the injection core type or the injection core type and the injection core type are mounted is driven reversibly and rotationally in different directions each time. This is because the circulating supply of the cooling medium to the cooling unit of each mold becomes easy.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic plan view of an apparatus according to an embodiment of the present invention.

 FIG. 2 is a bottom view of the turntable.

FIG. 3 is a schematic perspective view showing a release state of the injection core type in which the neck pressing plate is driven to descend.

FIG.4A is a side view showing the mold opening state of the device of the embodiment, FIG.
FIG. 5 is a side view showing a mold clamping state of the embodiment device.

FIG. 5 is a schematic cross-sectional view showing a mounting structure of the injection core type and the neck cavity type with respect to the turntable.

FIG. 6 is a schematic explanatory view of a preform take-out drive mechanism.

 FIG. 7 is an enlarged cross-sectional view of FIG. 6A.

FIG. 8 is a schematic explanatory view for explaining a release state of the injection core mold.

FIG. 9 is a schematic explanatory diagram for explaining the drive for taking out the preform.

BEST MODE FOR CARRYING OUT THE INVENTION One embodiment to which the method and apparatus of the present invention are applied will be specifically described below with reference to FIGS.

FIG. 1 is a plan view of the apparatus of the present embodiment. An injection device 12 is disposed on a machine base 10 shown in FIG. An extraction station 16 is provided adjacent.

Below the injection molding station 14, a lower mold clamping plate 20 fixed on the machine base 10 is provided as shown in FIGS. 4A and 4B. Above the lower clamping plate 20 and over the installation range of the injection molding station 14 and the cooling / unloading station 16, for example, a circular upper clamping plate 22 is arranged. The upper clamping plate 22 can be moved up and down along four tie bars 24 provided at four locations around the injection molding station 14. As shown in FIGS. 1, 4A and 4B, a fixing plate 26 is provided at the upper end of the tie bar 24, and a mold clamping cylinder 28 is fixed to the fixing plate 26. The mold clamping cylinder 28 drives the mold clamping rod 28a, and the upper mold clamping plate 22 is driven up and down by the mold clamping rod 28a.

4A and 4B, on the lower surface of the upper mold clamping plate 22,
The turntable 30 is rotatably supported. This turntable 30
5, is fixed to a rotating shaft 34 that is driven to rotate by a rotating actuator 32 fixed to the upper mold clamping plate 22. As shown in FIG. 2, which is a bottom view of the rotating disk 30, two rows of injection core dies 50 and neck cavity dies 60 are supported on the rotating disk 30 at positions corresponding to the stations 12, 14, respectively. . The details of the injection core mold 50 and the neck cavity mold 60 will be described later.

As shown in FIGS. 4A and 4B, the injection molding station 14 has a hot runner mold
Is provided, and an injection cavity mold 42 is fixed on the hot runner mold 40. This injection cavity mold 42
Has, for example, four cavities for the number of simultaneous moldings at the injection molding station 14. The injection cavity mold 42 is capable of cooling an injection-molded preform, and a coolant, for example, normal-temperature water is circulated in the cavity mold.

As shown in FIGS. 4 to 6, the two rows of injection core dies 50 supported by the rotating disk 30 have, for example, four core pins 52 in each row by the number of molded simultaneously. As shown in FIG. 5, the base end 52a of the core pin 52 is supported by a core pressing plate 54 fixed to the lower surface of the turntable 30 and a core fixing plate 56 fixed to the lower surface of the core pressing plate 54. Have been. The mold clamping cylinder 28 is driven, and the mold clamping rod 28a drives the upper mold clamping plate 22 to descend,
The rotating plate 30 and the core holding plate 54 supported by the upper mold clamping plate 22
Each of the core pins 52 of the injection core mold 50 is driven to descend integrally with the core fixing plate 56, and is driven to clamp the injection cavity mold 42.

Two rows of neck cavity molds 60 supported on a turntable 34
As shown in FIGS. 5 and 9, a pair of split dies 62a and 62b are provided, and a pair of split dies 62a and 62b are provided in each row as many as the number of simultaneous moldings. A pair of split dies 62a in each row,
Dividing plates 64a and 64b for fixing the respective 62b are provided, and the dividing plates 64a and 64b constitute a neck fixing plate 64. As shown in FIGS. 3 to 9, a neck pressing plate 65 for pressing and driving the neck fixing plate 64 downward is disposed on the upper surface side of the divided plates 64a and 64b. Further, guide plates 66 are provided for supporting the lower surfaces of both ends in the longitudinal direction of the neck fixing plate 6. The dividing plates 64a and 64b are set to be always closed by a spring 64c shown in FIG. As shown in FIG. 2, wedge holes 64d are provided at both ends in the longitudinal direction of each of the divided plates 64a and 64b. After the neck fixing plate 64 is carried into the cooling / unloading station 16,
Split-type opening cam 1 described later, which is driven toward the wedge hole 64d.
By 08, the split plates 64a and 64b are driven to open along the guide plate 66.

As shown in FIGS. 7 and 3 which are enlarged sectional views of the portion A in FIG. 6, an elevating pin 70 whose lower end is fixed to the guide plate 66 extends upward.
70a are formed. On the other hand, a guide cylinder 72 extending downward from the lower surface of the turntable 30 is fixed, and
Are arranged on the guide cylinder 72. Then, the bottom inner wall of the guide cylinder 72 and the flange 70a of the lifting pin 70
And a return spring 74 is disposed between them. Due to the upward biasing force of the return spring 74, the guide plate 66 is constantly moved upward and biased.
65 is always in close contact with the lower surface of the core fixing plate 56.

By maintaining the close contact state between the core fixing plate 56 and the neck pressing plate 65, the mold clamping state between the injection core mold 50 and the neck cavity mold 60 is set. Further, an external force (described later) applied at the cooling / unloading station 16 lowers the elevating pin 70 against the urging force of the return spring 74, and moves the neck pressing plate 65 away from the lower surface of the core fixing plate 56. , And presses the neck fixing plate 64 downward.
As a result, the neck cavity 2
The core pin 52 of the injection core mold 50 is driven to release from the preform 1 in which is held.

Next, a preform take-out drive mechanism in the cooling / take-out station 16 will be described. In the present embodiment, the preform take-out drive mechanism includes the neck release drive unit 80 and the split mold release drive unit 100. Neck release drive 8
0 has a first cylinder 82 as shown in FIG. 6, and the first cylinder 82 has a first cylinder fixing portion 84b supported on the upper mold clamping plate 22 via a first support 84a. It is fixed to. The first cylinder 82 has a first piston rod 82
The first lifting plate 86 is driven to move up and down via a.
Press drive rods 88 are provided on both ends of the first lifting plate 86 in the longitudinal direction. Meanwhile, the upper clamping plate
A hole 22a penetrating from the upper surface to the lower surface is provided in the 22, and the pressing drive rod 88 is disposed in the hole 22a. The initial position of the first elevating plate 86 is set at a position where the tip of the pressing drive rod 88 does not protrude from the lower surface of the upper mold clamping plate 22 so as not to hinder the rotational driving of the turntable 30.

As shown in FIG. 6, the turntable 30, the core holding plate 54, and the core fixing plate 56 have holes 30a, 54a, 56a at positions facing the holes 22a of the upper mold clamping plate 22, respectively. A driven rod 68 disposed in each of the holes 30a, 54a, 56a is fixed to the upper surface of the neck pressing plate 65.

Therefore, when the first cylinder 82 is driven, the first piston rod 82a, the pressing drive rod 88, and the driven rod
The neck pressing plate 65 and the neck fixing plate 64 are driven downward via the 68 against the urging force of the return spring 74. As a result, as shown in FIG. 8, the preform 1 in which the neck portion 2 is held by the neck cavity mold 60.
Accordingly, the core pin 52 of the injection core mold 50 is driven to release. In the present embodiment, the core pins 52 of the injection core mold 50 are used.
Does not need to be completely released from the opening end of the preform 1 as long as there is at least a gap between the core pin 52 and the inner wall of the preform 1 for air to enter. In the present embodiment, the downward stroke of the neck fixing plate 64, that is, the release stroke (the length L shown in FIG. 8) of the core pin 52 is set to, for example, 50 mm.

Next, the split mold opening drive unit 100 will be described. The split mold opening drive unit 100 has, for example, two second cylinders 102, as shown in FIGS. As shown in FIG. 9, the second cylinder 102 includes a second cylinder fixing plate 104b supported by a first lifting plate 86 via a second support 104a.
It is fixed to. Therefore, when the first lifting plate 86 is driven to move up and down by the first cylinder 82, the second cylinder 102 is also driven to move up and down. The second cylinder 102 drives the second lifting plate 106 up and down via a second piston rod 102a. Split-type opening cams 108 are fixed to the second lifting plate 106 at both ends in the longitudinal direction. This split-type opening cam 108
The lower ends of the split plates 64a, 64b constituting the neck fixing plate 64
It has a wedge shape corresponding to the wedge hole 64d provided in. Therefore, by driving the second cylinder 102, the split mold opening cam 108 is driven downward, and the wedge portion at the tip thereof can be inserted into each of the wedge holes 64d of the neck fixing plate 64. The plates 64a and 64b are driven to open. Then, the pair of split dies 62a, 62b fixed respectively to the pair of split plates 64a, 64b are driven to open, and the preform 1 is taken out from the neck cavity die 60. In this embodiment, the second cylinder 102
Is set after the first cylinder 82 is driven.

Next, the injection molding operation of the preform 1 in the apparatus of the embodiment will be described.

(1) Injection molding process in the injection molding station 14 By driving the mold clamping cylinder 28 to lower the upper mold clamping plate 22, the injection core mold and the neck cavity mold 60 are mold-clamped with respect to the injection cavity mold 42. Is done. After the clamping state shown in FIG. 4 is set, the screw in the injection device 12 is driven forward and rotationally to make the injection molding material of the preform 1, for example, polyethylene terephthalate (PET).
However, via the hot runner mold 40, each mold 42, 50 and 60
And the injection molding of the preform 1 is performed.

(2) Cooling process at the injection molding station The injection cavity mold 42, the injection core mold 50, and the neck cavity mold 60 each circulate a coolant, for example, normal-temperature water, and can immediately cool the resin filled in the cavity. It is.

(3) Injection cavity mold at injection molding station 14
The mold release process of 42 The mold cavity cylinder 28 is driven to drive the upper mold clamping plate 22 upward, and as shown in FIG.
The injection core mold 50 and the neck cavity mold 60 can be driven upward with respect to 42. At this time, preform 1
Since the neck portion 2 forms an undercut in the mold release direction, the injection-molded preform 1 is held by the injection core mold 50 and the neck cavity mold 60, and is released from the injection core mold 42. Will be.

The mold release start timing at the injection molding station 14 can be sufficiently earlier than the conventional mold release start timing. In other words, the cooling time of the preform 1 at the injection molding station 14 can be reduced. This is because even after the injection cavity mold 42 is released from the preform 1, the state in which the core pins 52 of the injection core mold 50 are inserted into the preform 1 can be maintained, and the deformation accompanying the heat shrinkage of the preform 1 can be maintained. This is because it can prevent. Therefore, the release temperature of the preform 1 at the injection molding station 14 is
The temperature at which the skin layer is formed on the surface of the preform 1 so that the shape can be maintained even after the injection cavity mold 42 is released may be higher than the conventional release temperature. Even at such a high mold release temperature, the preform 1 contracts to the side of the injection core mold 50 which is in close contact with the core pin 52 by cooling, so that the mold release from the injection cavity mold 42 can be performed relatively smoothly. And the mold release failure of the preform 1 does not occur. Also, at the injection molding station 14, the core pins 52
Therefore, even if the preform 1 is released at a high release temperature, a release failure in which the lower end of the preform 1 is wound up together with the core pins 52 does not occur.

The mold clamping state of the injection core mold 50 and the neck cavity mold 60 with respect to the preform 1 from which the injection cavity mold 42 has been released is determined by the return spring 74 and the core fixing plate 56.
And it is maintained by bringing the neck pressing plate 65 into a close contact state. The mold-clamped state of the injection core mold 50 and the neck cavity mold 60 passes through the subsequent preform 1 conveying process,
This is maintained until the injection core mold 50 is driven to be released from the cooling / unloading station 16. Therefore, the preform 1 can be cooled while the injection core mold 50 and the neck cavity mold 50 are maintained in the closed state.

(4) Preform 1 transport process Cooling / unloading station from injection molding station 14
The transport of the preform 1 toward 16 is performed by driving the rotary actuator 32 to rotate the turntable 30 by 180 °. In the process of transporting the preform 1,
The cooling of the preform 1 can be continued by the refrigerant circulating through the injection core mold 50 and the neck cavity mold 60.

By the way, when the preform 1 is released at a high temperature,
Crystallization occurs due to insufficient cooling, which causes a problem that the wall surface of the preform 1 becomes opaque, which is a fatal defect particularly when a transparent container is molded using PET. According to experiments performed by the present inventors, it has been found that crystallization and opacity of the preform 1 due to insufficient cooling are more remarkable on the inner wall side of the preform 1. This is due to the fact that the contact area with the mold is smaller on the inner wall side of the preform 1, and the inner wall is less cooled than the outer wall.
Further, when the injection cavity mold 42 and the injection core mold 50 are released from the preform 1 at the injection molding station as in the prior art, the heat radiation area on the inner wall side of the preform 1 is smaller, and the preform This is because heat is trapped inside 1 and the inner wall side is insufficiently cooled compared to the outer wall.

In the present embodiment, even if the preform 1 is released from the injection molding station 14 at a relatively high temperature, the preform 1 can be continuously cooled by the injection core mold 50 and the neck cavity mold 60 in the subsequent transport process. it can. In particular, since the inner wall of the preform 1 can be continuously cooled by the core pins 52 of the injection core mold 50, crystallization and opacity due to insufficient cooling can be reliably prevented. In addition, the neck portion 2 has a large heat capacity due to its thick wall and is easily crystallized.
Is cooled by the neck cavity mold 60 to prevent crystallization.

(5) Cooling Step of Preform in Cooling / Unloading Station Even after the preform 1 is carried into the cooling / unloading station 16, the injection core mold 50 and the neck cavity mold 60 maintain the mold clamping state with respect to the preform 1. The preform 1 can be cooled in the same manner as in the above transporting step. At this time, in the injection molding station 14, even if the mold clamping cylinder 28 is driven to lower the upper mold clamping plate 22 for injection molding of the next preform, the above-described mold clamping state in the cooling / unloading station 16 is performed. Is maintained, the cooling of the preform 1 can be continued.

(6) Release process of neck cavity mold 60 from injection core mold 50 Cooling of preform 1 by core pins 52 of injection core mold 50 prevents crystallization caused by insufficient cooling of the inner wall of preform 1 and ejects the same. A cooling time sufficient to prevent the deformation of the preform 1 may be sufficient. Conversely, if the preform 1 is supercooled by the core pins 52, it becomes difficult to drive the core pins 52 out. Therefore, in the cooling / unloading station 16, first, the injection core mold 50 is driven to be relatively released from the preform 1. In this embodiment, the neck cavity mold 60 holding the preform 1 is used.
Is driven to release from the injection core mold 50.

The release of the neck cavity mold 60 is performed by lowering the neck pressing plate 65, which is kept in close contact with the core fixing plate 56 by the moving urging force of the return spring 74, by the neck release driving unit 80. Done. When the first cylinder 82 of the neck release drive unit 80 is driven, the pressing force of the first piston rod 82a, the first lifting plate 86, the pressing drive rod 88, and the driven rod 68 causes the first cylinder 82 to move as shown in FIGS. As shown in FIG. 8, the neck fixing plate 64 is pressed by the neck pressing plate 65 to be driven downward. At this time, since the neck portion 2 of the preform 1 is held by the neck cavity mold 60, the preform 1 is also attached to the neck fixing plate.
It is driven down together with 64 and the neck cavity mold 60. Therefore, the injection core mold 50 is moved to the preform 1 by the relative release driving of the neck cavity mold 60 and the injection core mold 50.
It will be released more.

The release stroke of the injection core mold 50 with respect to the preform 1 is such that the core pin is completely removed from the open end of the preform 1 for the subsequent conveyance of the preform 1 as in the prior art.
The mold 52 is not required to be released, but it is sufficient that the gap is formed at least so that air enters between the core pin 52 and the inner wall of the preform 1. Therefore, the release stroke of the injection core mold 50 depends on the angle of the extraction taper formed on the core pin 52 and the inner wall of the preform 1, and the greater the angle of the extraction taper, the smaller the amount of release stroke. As described above, since the release stroke of the injection core mold 50 can be shortened, the installation height of the first cylinder 82 can be reduced, and the overall height of the injection molding device can be reduced, thereby reducing the transportation and installation of the device. This is advantageous.

(7) Step of removing preform The preform 1 has a neck portion 2 having a pair of split dies 62a,
Since it is held by the neck cavity mold 60 constituted by 62b, the preform 1 is taken out by driving the neck cavity mold 60 to release. For this,
The second cylinder 102 of the split mold opening drive unit 100 is driven.
The driving force of the second cylinder 102 is transmitted to the split opening cam 108 via the second piston rod 102a and the second elevating plate 106. When the split mold opening cam 108 is driven to move downward, the tip ends thereof form a pair of split plates 64a and 64b as shown in FIG.
Are inserted into the wedge holes 64d formed in
By opening the 4b, the pair of split dies 62a and 62b are opened. At this time, even if one split mold 62a, 62b
Even if the neck portion 2 of the preform 1 moves in close contact with the preform 1, if the core pin 52 of the injection core mold 50 remains in the preform 1, this causes the preform 1 to move in the lateral direction. Is restricted, and the preform 1 can be reliably dropped.

Further, in a state before the split mold opening cam 108 is driven to descend, in order to avoid interference at the time of rotational driving of the turntable 30, the tip thereof must be stopped within the thickness range of the upper mold clamping plate 22. No. On the other hand, since the neck fixing plate 64 that is opened and driven by the split mold opening cam 108 is located farthest from the turntable 30, the downward stroke of the split mold opening cam 108 becomes longer. In the present embodiment, the second cylinder 102 for driving the split mold opening cam 108 is fixed to a first elevating plate 86 driven by the first cylinder 82, and the split mold opening cam 108
Since the first raising / lowering plate 86 is driven to lower before the driving, the substantial lowering stroke of the split mold opening cam 108 can be shortened. Thus, the installation height of the second cylinder 102 can be reduced, and the overall height of the injection molding machine can be reduced, thereby providing a device that is advantageous in terms of transportation and installation.

After the step of removing the preform 1 is completed, the first and second cylinders 82 and 102 are returned to the initial state. As a result, the neck pressing plate 65 is brought into close contact with the core fixing plate 56 by the return spring 74, and the injection core mold 50 and the neck cavity mold 60 can be returned to the mold clamped state in preparation for the next preform injection molding.

The cooling and demolding process in the above-described cooling and unloading station 16 is completed until the injection molding of the next new preform is completed in the injection molding station 14, in other words, within the injection molding cycle time. Good. The cooling time of the preform 1 depends particularly on the thickness of the body of the preform 1, and it is necessary to secure a longer cooling time as the thickness of the preform 1 increases. In this embodiment, in addition to adjusting the cooling time in the injection molding station 14, the cooling time
It can be adjusted by setting the release timing of the injection core mold 50 in the unloading station 16. Therefore, while the mold release temperature in the injection molding station 14 is increased to shorten the injection molding cycle, the adjustment of the cooling time is easy, so that a highly versatile injection molding apparatus can be provided.

After the injection molding of the preform 1 in the injection molding station 14 is completed, the rotating disk 30 is moved to the rotary actuator 32.
The two stations 14,
The injection core mold 50 and the neck cavity mold 60 are exchanged for 16. In this embodiment, the rotary actuator 32 is constituted by a reversible rotary transport unit in which the rotational transport direction is changed each time. Therefore, even if the cooling pipe for circulating the refrigerant is connected to the injection core mold 50 and the neck cavity mold 60 which are rotated and conveyed, this cooling pipe is one piece.
No more twisting than rotation. Therefore, the connection of the cooling pipe to the mold can be performed without using a rotary connector or the like, and the configuration is not complicated.

(8) Blow molding step A blow molding apparatus is connected to the preform injection molding apparatus described above, and the preform 1 which retains heat during injection molding.
Can be blow-molded into a hollow body such as a bottle by a so-called hot parison method.

In this case, the preform 1 taken out at the cooling / unloading station 16 is received by means for supporting the neck portion or the like, and is conveyed to the blow molding station. On the way to the blow molding station, the temperature of the preform 1 may be controlled to give the preform 1 a temperature distribution for improving the thickness distribution.

In the blow molding station, the preform 1 is blow molded by a known method to form a bottle. That is, the preform 1 is placed in a blow cavity mold,
The preform 1 is biaxially stretched by longitudinal stretching by a stretching rod and blowing air from a blow core mold.

At this time, since the preform 1 is given a uniform temperature or an appropriate temperature distribution for the above-described reason, a bottle having a desired thickness can be formed. Further, whitening and crystallization of the bottle are prevented from occurring, and a highly transparent bottle can be formed. In addition, the present invention is not limited to the above-described hot parison blow molding method, but may be applied to a so-called cold parison blow molding method in which the preform 1 is once returned to room temperature and then heated and blow molded. Of course, it can be applied. Also in this case, there is an effect that the injection molding cycle time of the preform can be shortened.

It should be noted that the present invention is not limited to the above embodiments, and various modified embodiments are possible within the scope of the present invention.

In the above embodiment, the injection core mold 50 and the neck cavity mold 60 are conveyed by the turntable 30. However, for example, when the shape of the neck portion 2 is not undercut in the releasing direction, the neck cavity mold 50 is not necessarily used. You do not need to use 60. In this case, after the injection cavity mold 42 is released from the injection molding station 14, the preform 1 may be conveyed to the cooling / unloading station 16 only by the injection core mold 50. Preform 1 is cooled by injection core mold 50
The injection cavity mold 42 can be smoothly released from the mold, and the preform 1 can be conveyed by the injection core mold 50 even if the neck portion 2 does not have an undercut. .

At the cooling / unloading station 16, the preform 1
In order to release the injection core mold 50 more, for example, the following method can be adopted. That is, the core pin 52 of the injection core mold 50 is
What is necessary is just to have the function which can introduce the air for eject drive into the preform 1. In this case, at the cooling / unloading station 16, after the preform 1 is cooled by the injection core mold 50, air is blown out by the core pins 52, so that the preform 1 can be dropped downward by the air pressure. .

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI B29C 49/42 B29C 49/42 (56) References JP-A-57-93126 (JP, A) JP-A-57-105321 (JP) US Patent 3,337,667 (US, A) US Patent 3,816,580 (US, A) US Patent 3,966,378 (US, A) US Patent 4,107,362 (US, A) US Patent 4,472,131 (US, A) US Patent 5,080,574 (US, A) US Pat. No. 5,403,177 (US, A) US Pat. No. 5,501,593 (US, A) US Pat. No. 4,615,667 (US, A) US Pat. No. 4,867,671 (US, A) US Pat.

Claims (15)

(57) [Claims] 1. a step of clamping an injection cavity mold having a cooling portion, a neck cavity mold comprising a pair of split molds and an injection core mold at an injection molding station to injection-mold a preform; A step of releasing the injection cavity mold from the preform at a station; a step of transporting the preform to a cooling / unloading station while cooling the preform by the injection core mold and the neck cavity mold; In the cooling / unloading station, the preform is cooled by the injection core mold and the neck cavity mold before the injection molding of the next preform is completed, and thereafter, the injection core mold and the neck are cooled. Removing the preform from the cavity mold; and In the unloading step at the station, the neck cavity mold is moved relative to the injection core mold by an amount of stroke sufficient to create a gap between the inner wall of the preform held by the neck cavity mold and the injection core mold. A method of injection-molding a preform, wherein the preform is taken out by relatively driving the mold release and then opening and driving the pair of split dies of the neck cavity mold. 2. The preform removal step according to claim 1, wherein the preform removing step is such that the preform adheres to one of the pair of split molds by the injection core mold remaining in the preform. A method for performing injection molding of a preform, wherein the method is performed while restricting movement in the opening drive direction. 3. The method according to claim 1, wherein the adjustment of the cooling time of the preform is performed by adjusting the timing of the release driving at the cooling / unloading station. Preform injection molding method. 4. The injection core mold and the neck cavity mold according to any one of claims 1 to 3, wherein the injection molding station and the cooling / unloading station which are 180 degrees apart from each other by a rotation angle are provided. Are rotated reversibly together, and the injection core mold and the neck cavity mold are exchanged and transported to the two stations. 5. The method according to claim 1, wherein in the transporting step, the neck cavity mold is brought into close contact with the injection core mold by a return spring, and the molds are clamped in a closed state. In the cooling / unloading station, the neck cavity mold holding the preform is separated from the injection core mold by an external force against the urging force of the return spring, and the preform is taken out. Injection molding method for preform. 6. The injection cavity mold releasing step according to claim 1, wherein the injection cavity mold is separated from an outer surface of the preform cooled by the injection cavity mold. An injection molding method for a preform, which is performed after a skin layer capable of maintaining the outer shape of the preform even after mold release is formed. 7. A step of clamping an injection cavity mold, an injection core mold, and a neck cavity mold each having a cooling section, and then filling a molding material to injection-mold a preform; A step of releasing from the injection cavity mold; a step of rotating and transporting the preform while cooling the preform by the injection core mold and the neck cavity mold; Removing the preform from the injection core mold and the neck cavity mold in the injection molding method. 8. The preform taken out after being injection-molded by the method according to any one of claims 1 to 7 is blow-molded while retaining heat during the injection molding. Transferring the preform in a blow cavity mold at the blow molding station, and blowing the hollow body from the preform by driving the longitudinal axis of the stretching rod and introducing air from the blow core mold. A blow molding method, comprising the steps of: 9. A preform injection molding apparatus, comprising: an injection molding station for injection molding a preform; and a cooling / removing station for removing the preform by releasing after cooling. A neck cavity mold comprising a pair of split molds and an injection core mold each having a cooling function for the preform, each being disposed at a corresponding position; and exchanging and transporting the injection core mold and the neck cavity mold to each of the stations. Exchange conveying means, the injection core mold and the neck cavity mold arranged at the injection molding station are clamped with an injection cavity mold having a preform cooling function, and the injection core mold at the injection molding station, Neck cavity mold and injection cavity mold are driven for mold clamping, and A mold clamping unit that relatively releases the injection cavity mold with respect to the preform, and the preform arranged at the cooling / unloading station is cooled by the injection core mold and the neck cavity mold. And a take-out drive means for taking out and driving the preform from the injection core mold and the neck cavity mold, wherein the take-out drive means comprises: the preform inner wall held by the neck cavity mold; and the injection core. Mold release driving means for relatively releasing the neck cavity mold with respect to the injection core mold by a stroke amount sufficient to generate a gap between the mold and the injection core mold, and after the relative mold release drive of the neck cavity mold, Split mold opening means for opening and driving the pair of split molds to take out the preform. Injection molding apparatus. 10. The cooling apparatus according to claim 9, wherein the exchange transporting means comprises: an injection molding station provided at a position 180 ° apart by a rotation angle;
An injection molding apparatus for a preform, comprising: a rotating plate for intermittently rotating and transporting the injection core mold and the neck cavity mold to an unloading station. 11. The mold release driving means according to claim 10, further comprising: a return spring for moving and urging the neck cavity mold toward the injection core mold side to maintain both molds in a mold-clamped state. The present invention provides an injection molding apparatus for a preform, wherein a neck cavity mold is driven to be released relatively to the injection core mold against a biasing force of the return spring. 12. The method according to claim 11, wherein the two split plates respectively supporting the pair of split dies constituting the neck cavity die, and the two split plates are guided and supported so as to be able to come and go, A guide member to which the return spring is connected; a pressing plate disposed on the two split plates; and a length that stands upward on the pressing plate and whose upper end does not reach the rotary plate. A driven shaft, wherein the release driving means has a through-hole provided in the rotating disk at a position facing the driven shaft, and a lower end above the through-hole. A drive shaft, and a first drive unit that pushes and drives the drive shaft, wherein the drive shaft protrudes downward through the through-hole of the turntable by driving of the first drive unit. The lower end of the cylinder pushes the driven shaft, thereby forming the neck cavity mold. The injection molding apparatus of a preform and drives detachment from the injection core mold against the biasing force of the return spring. 13. The driving device according to claim 12, wherein each of the two split plates has a cutout in which opposing ends thereof are cut out in a wedge shape, and the driving force is generated by the driving force of the first driving unit. An elevating plate that moves up and down together with the shaft is provided, wherein the split mold opening driving means includes: a second driving unit mounted on the elevating plate; and a lower drive by the second driving unit. And a cam plate having a wedge-shaped tip portion adapted to the formed notch portion. 14. The injection of a preform according to claim 10, wherein said rotary disk is driven reversibly by changing the direction of rotation and transport each time. Molding equipment. 15. A preform injection molding apparatus having an injection device, an injection molding station, and a cooling / unloading station arranged on a machine base, wherein the injection molding station and the cooling machine are provided above the machine base. An upper clamping plate and a rotating plate are arranged so as to be able to move up and down over the position of the unloading station. A cavity mold, wherein the injection molding station has a lower mold clamping machine fixed on the machine base, wherein the lower mold clamping machine has a hot runner mold and an injection cavity mold. Preform injection molding equipment.