JPH05131443A - Injection mold for preform having undercut in lip part and synthetic resin vessel - Google Patents

Abstract

PURPOSE:To provide an injection mold where a preform having an undercut in a mouth part can be molded and smooth mold release can be realized and a form of a mouth part of a resinous vessel where mold release after injection molding can be realized more smoothly. CONSTITUTION:In a mouth part 22 of a preform having an undercut 18, its inner wall is regulated by the second injection core mold 40 and in its outer wall, a nonundercut area is regulated by the first lip cavity mold 60 and an undercut area is regulated by the second lip cavity mold 70. In mold release after injection molding, the second lip cavity mold 70 is moved upward and a space where no interference member is in existence is secured on the outer circumference of the undercuit 18. After the space is securred, the second injection core mold 40 is raised and moved and the mold release by forced pulling-off of the second injection core mold 40 is realized while the undercuit 18 is being deformed outward elastically by making use of the above-mentioned space.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a preform injection molding die having an undercut in a lip portion and a biaxially stretch blow-molded synthetic resin container having such a rib portion.

[0002]

2. Description of the Related Art A roll-on type container is a container in which a sphere is rotatably housed on the opening side of a container, and the liquid inside the container is applied to the paper while the container is inverted and the sphere is in rotary contact with the paper or the like. Known as. When molding such a container from synthetic resin, the opening side of the container must be an undercut shape that extends inward toward the opening end.

When molding a hollow container, whether in injection blow molding or stretch blow molding, first, a preform having a bottomed cylindrical body and a lip portion on the opening end side is formed by injection molding. To do.
Then, blow air is introduced into the body of the preform to blow mold the synthetic resin container. In the case of stretch blow, vertical axis stretching with a stretch rod is also performed.

In the case of the stretch blow molding method, the injection molding of the preform is carried out by using an injection core mold that defines the inner wall of the lip and the body of the preform, an injection cavity mold that defines the outer wall of the body, and a lip. And a lip cavity mold that defines the outer wall of the part. Then, resin is filled between the outer wall surface of the injection core mold and the cavity surfaces of the injection cavity mold and the lip cavity mold to injection-mold the preform. Thereafter, for example, the injection core mold and the lip cavity mold are moved upward to take out the preform from the injection cavity mold, and then the injection core mold is pulled out from the inside of the preform to take out the preform.

In order to mold a roll-on type container, an undercut must be formed on the lip portion of the preform so as to project inward toward the open end side. Therefore, an undercut area is defined between the lip cavity mold and the core mold.

However, it is impossible to release the mold with such a mold structure. That is, when the injection core mold is pulled out from the inside of the preform, the undercut is damaged and the mold is also damaged. At this time, the pair of lip cavity molds configured as split molds that can be opened and closed in the left-right direction is the only means for holding the preform. Therefore, it is not allowed to release the pair of lip cavity molds in the injection molding process. Therefore, since the preform is held by the lip cavity mold when the injection core mold is released, there is no space around the undercut where the undercut elastically deforms.

On the other hand, in the case of the injection blow molding method, the injection core mold, which also serves as a blow air introduction means, is finally released from the blow molded container. Therefore, a space for elastically deforming the undercut area of the lip portion can be secured in the periphery. However, in the conventional injection blow molding method, the resin material that can be released by elastically deforming such an undercut area is limited to a relatively soft material such as polypropylene or polyethylene. There were restrictions on materials. Further, since injection blow molding is not biaxially stretch blow molding like stretch blow molding, it is also inferior in terms of mechanical strength of the container.

[0008]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to perform injection molding of a preform used in biaxial stretch blow molding and having a lip portion with an undercut. Moreover, it is to provide an injection molding die capable of releasing the core die without damaging the undercut.

Another object of the present invention is to provide an injection molding die capable of releasing the core die by elastically deforming the undercut formed in the lip portion even in the case of a relatively hard resin material. Especially.

Still another object of the present invention is to:
An object of the present invention is to provide a synthetic resin container in which an undercut portion is formed in a lip portion during injection molding, and a body portion thereof is biaxially oriented.

[0011]

Means for Solving the Problem and Its Action The present invention is
It has a tubular body with a bottom and a lip on the open end side,
The lip part is an injection molding die for injection-molding a preform in which an undercut protruding inward is formed toward the opening end side, and has an outer shape defining an inner wall of the lip part and the body part. An injection core mold that is moved in the longitudinal direction relative to the preform, and a cavity surface that defines the outer wall of the body, and is moved in the longitudinal direction relative to the preform And a cavity surface that is disposed adjacent to the injection cavity mold when the mold is closed and that defines the outer wall of the non-undercut area of the lip portion, and is moved in opposite horizontal axis directions. A first lip cavity mold configured as a pair of split molds, and a first lip cavity mold which is arranged adjacent to the first lip cavity mold when the mold is closed, and which forms an outer wall of an undercut area of the lip portion. It has a cavity surface for the constant, second to be moved relative longitudinal axis direction with respect to the preform
Of the lip cavity mold, and at the time of mold release, the initial movement for relative mold release of the second lip cavity mold in the vertical axis direction is performed by the initial movement amount for securing a space around the undercut area. And a mold driving mechanism for performing relative mold-releasing movement of the injection core mold in the vertical axis direction while elastically deforming the undercut area to the outside.

According to the present invention, the lip cavity mold defining the outer wall of the lip portion is divided into two. The first lip cavity mold, which is configured as a pair of split molds, defines the outer wall of the non-undercut area of the lip portion, which is not separated even after the injection molding of the preform and the lip portion of the preform. It is possible to hold On the other hand, the second lip cavity mold has a cavity surface defining the outer wall of the undercut area of the lip portion, and after injection molding of the preform, the relative axial movement of the preform causes the outer circumference of the undercut area. Space can be secured.

The undercut of the lip portion is formed in the cavity between the second lip cavity mold and the injection core mold. Then, at the time of mold release, the initial mold release drive of the second lip cavity mold is performed prior to the mold release drive relative to the preform of the injection core mold in the vertical axis direction. As a result, since the undercut can be elastically deformed toward the space side around it when the injection core mold is driven to be released, it is possible to realize the mold release by forcibly removing the injection core mold.

Moreover, this releasing operation is carried out immediately after the injection molding of the preform is completed. Therefore, the elastic deformation of the undercut area is performed by utilizing the heat retained by the lip portion during injection molding. Therefore, even if the preform is injection-molded with a relatively hard resin material, the undercut does not break.

The synthetic resin container according to the present invention is obtained by biaxially stretch-blow molding a lip portion formed on the opening side when a bottomed tubular preform is injection-molded and a body portion of the preform. A bottomed cylindrical biaxially oriented body portion, and the lip portion rotatably accommodates and holds a sphere, and extends outward toward the lip portion opening end. A first wall portion that contacts the lower hemisphere of the sphere, and a second wall that is formed in an undercut shape that extends inward toward the opening end of the lip portion and that contacts the upper hemisphere of the sphere. And a plurality of slits cut out from the free end portion of the second wall portion toward the base end thereof are provided in the circumferential direction.

According to such a container, in the spherical body rotatably housed in the lip portion, the lower hemisphere rolls on the first wall portion and the second wall portion in contact with the upper hemisphere of the spherical body is provided. Since it is shaped like an undercut, it can be stored rotatably while preventing the sphere from coming off. This container is molded by biaxial stretch blow molding, and the lip portion is injection-molded in the preform injection molding process as a pre-process. At this time, since the second wall portion having the undercut shape is provided with a plurality of slits of a predetermined length cut out from the free end portion toward the base end in the circumferential direction, the injection core type unreasonable The second wall portion is likely to be elastically deformed at the time of releasing from the die, and it is possible to realize molding of a defective molded product with a high yield. Moreover, the elastic deformation of the undercut area is carried out by utilizing the heat retained during injection molding. Therefore, even if the preform is injection-molded with a relatively hard resin material, the undercut does not break.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a preform injection molding die to which the present invention is applied will be specifically described below with reference to the drawings.

The container 10 shown in FIG. 6 has a preform 20.
Is obtained by biaxial stretching blow molding. The container 10 has a lip portion 12 on the open end side of the body portion 14, and the sphere 16 is rotatably accommodated in the lip portion 12. The body portion 14 is biaxially oriented, and the mechanical characteristics are improved by orientation crystallization. The container 10 is a so-called roll-on type container in which the liquid inside is gradually applied to the object to be coated when the sphere 16 is brought into contact with the object to be coated while the container 10 is inverted. ..

In order to mold such a container 10,
An undercut 18 that protrudes inward as it goes toward the opening end side must be formed at the opening end of the lip portion 12. A preform 20 for biaxially stretch-blow molding the container 10 is provided with a lip portion 12 of the container 10 on the open end side of a bottomed cylindrical body portion 24 as shown by a chain line in FIG.
It is necessary to have a lip portion 22 having substantially the same shape as the above. Therefore, the undercut 18 in the lip portion 22
Must be molded in the injection molding process of the preform 20.

FIG. 1 is a sectional view of an injection mold of a preform 20 which is a preform for molding the container 10 shown in FIG. This injection mold is roughly divided into a first injection core mold 30, a second injection core mold 40, an injection cavity mold 50, a first lip cavity mold 60 and a second lip cavity mold 70.

The first injection core mold 30 is the preform 2
A rod-shaped core pin portion 32 that defines the inner wall of the body portion 0 of 0;
The core pin portion 32 has a base end portion 34 having a larger diameter, and the upper end of the base end portion 34 is configured as a flange 36 having a larger diameter than the base end portion 34. The first injection core mold 30 can be released from the preform 20 in the direction of arrow A in FIG. The core pin portion 32
It is also possible to circulate a cooling medium inside.

The second injection core die 40 has a tubular portion 42 which is inserted into the core pin portion 32 of the first core die 30,
A bulge portion 44 that defines the inner wall of the lip portion 22 of the preform 20 is provided on the tip end side of the tubular portion 42.
Further, a flange 46 having the same diameter as the base end portion 34 of the first injection core mold 30 is provided on the upper end of the tubular portion 42. The injection cavity mold 50 has a cavity surface 52 that defines the outer wall of the body 24 of the preform 20 and the shoulder 26 above it. A gate opening 54 opening to the cavity surface 52 is provided at the center of the lower end of the injection cavity mold 50, and a refrigerant jacket 56 is built in so as to surround the cavity surface 52. The injection cavity mold 50 can be driven to be released from the preform 20 in the direction of the arrow B in the figure. In this embodiment, the injection cavity mold 50 is fixed and the preform 20 is injected. The cavity mold 50 is pulled out and driven.

The first lip cavity mold 60 is constructed as a pair of split molds 62a and 62b which can be opened in the directions of opposite arrows C ₁ and C _{2 in the} horizontal axis direction of FIG. , 62b have a cavity surface 64 that defines an outer wall of a lower region of the lip portion 22 of the preform 20 that does not include the undercut 18. The first lip cavity mold 60 is supported by a support plate 66 so as to be openable and closable, and after the preform 20 is injection-molded in the injection process, the next process, for example, a temperature control process is performed while the preform 20 is held. After that, the preform 20 can be conveyed to the biaxial stretch blow molding process.

The second lip cavity mold 70 is formed as a hollow cylindrical portion 71 so as to surround the first and second injection core molds 30 and 40, and the lip of the preform 20 is provided on the lower end side thereof. It has a cavity surface 72 that defines the outer wall of the opening end side of the portion 22, that is, the region including the undercut 18. The flange 76 provided on the upper end of the tubular portion 71 is fixed to the flange 36 of the first injection core mold 30, so that the first injection core mold 30 and the second lip cavity mold 70 are integrated. Mold release driving is possible in the direction of arrow A in FIG. Further, on the inner wall of the tubular portion 71 of the second lip cavity mold 70, a step surface 74b is provided at a position that is higher than the bottom wall inner surface 74a by a predetermined height. A coil spring 78 is provided between the inner surface 74a of the bottom wall and the flange 46 of the second injection core mold 40, and constantly urges the second lip cavity mold 70 to move downward.

Next, the injection molding step of the preform 20 in this injection molding die and the subsequent releasing step will be described.

After closing and driving each mold in the state shown in FIG. 1,
A resin material heated and melted, for example, poly-ethylene terephthalate (PET), is filled at a predetermined pressure through the gate opening 54, and the preform 20 is injection-molded. After that, after a predetermined cooling time in the injection cavity mold 50 has passed, the mold release driving of each mold is started.

In this embodiment, since the injection cavity mold 50 is fixed, the support plate 66 is moved upward, and as a result, the first and second injection core molds 30 and 40 and the first and second injection core molds 30 and 40 are moved.
The second lip cavity molds 60 and 70 are integrally raised, and the preform 20 is taken out from the injection cavity mold 50 and driven.

After the release driving, or in parallel with the release driving, the first injection core mold 30 is driven to release in the direction of arrow A in FIG. The first injection core mold 30 is formed by connecting the flanges 36 and 76 to the second lip cavity mold 7.
Since it is integrated with 0, the first injection core mold 30 and the second lip cavity mold 70 integrally rise in the direction of arrow A. The state after this initial movement is shown in FIG. 2A.
Is shown in.

As shown in the figure, the first injection core mold 30
And, the second lip cavity mold 70 rises integrally, but the second injection core mold 40 does not rise integrally and remains at that position. This is because the bulging portion 44 of the second injection core mold 40 is prevented from moving upward by the undercut 18 of the preform 20, and accordingly, the flange 46 of the second injection core mold 40 is moved during this movement. Thus, the coil spring 78 provided between the inner surface 74a of the bottom wall of the second lip cavity mold 70 is compressed. As shown in FIG. 2A, after the initial movement, the preform 2
On the outer periphery of the undercut 18 of 0, the second lip cavity mold 70 has no positional relationship at all. Therefore, the step surface 74 of the second lip cavity type shown in FIG.
The relationship between b and the distance H ₁ between the lower surface of the flange 46 of the second injection mold 40 and the required height H ₂ for securing a space on the outer periphery of the undercut 18 is H ₁ > H ₂ . Is becoming

After the initial movement in the state shown in FIG. 2A, the first injection core mold 30 is further driven upward. Then, the step surface 74b of the second lip cavity mold 70 that integrally rises with the first injection core mold 30 pushes up the second injection core mold 40, and the three molds are integrally driven to rise. Will be done.

The state at this time is shown in FIG. 2B. In this case, the bulging portion 44 of the second injection core mold 40 rises, but at this time, since the undercut 18 of the preform 20 has no interference member on its outer periphery,
It is possible to sufficiently reduce the resistance force that acts to hinder the upward movement of the bulging portion 44 by elastically deforming to the outside. Therefore, in spite of the presence of the undercut 18 of the preform 20, it is possible to drive the second injection core mold 40 having the bulging portion 44 by releasing the mold by force. Moreover,
This releasing operation is performed immediately after the injection molding of the preform 20. Therefore, the lip portion 22 retains the heat at the time of injection molding, and the elastic deformation of the undercut 18 can be performed by utilizing the retained heat. This becomes clearer when compared with the injection blow molding method. In the injection blow molding method, the mold releasing operation of the core pin is performed after the injection molding of the preform is completed and then the blow air is introduced into the preform from the core pin to blow mold the final container. During this period, the core pin controls the temperature of the preform to a temperature lower than the temperature immediately after injection molding. Therefore, when releasing the core pin, the neck portion is sufficiently cooled by the core pin.

As described above, in the case of the present embodiment, the elastic deformation of the undercut 18 during the releasing operation of the core mold can be performed by utilizing the heat retained in the lip portion during the injection molding of the preform. Compared with the injection blow molding method,
Even if the preform is molded with a hard resin material, the undercut 18 is not damaged. Therefore, polyethylene (PE) having a tensile elastic modulus of 7,000 to 10,000 Kgf / cm ² or a tensile elastic modulus of 11,000 to 16,000 Kg, which has been used in conventional injection blow molding.
The resin material is not limited to a resin material such as polypropylene (PP) of f / cm ² , and a resin material that matches the characteristics required for the final container can be selected. As a result, in addition to PE and PP, even in a hard resin material whose tensile elastic modulus is defined as 7,000 Kgf / cm ² or more, the tensile elastic modulus that could not be used in the injection blow molding method was 180.
Even if a hard resin material of 00 Kgf / cm ² or more is used as the resin material of the preform, a container without damage to the undercut 18 can be molded. Especially, the tensile modulus is 2300
It is 0 to 29000 Kgf / cm ² , and it is of great significance to use PET, which can obtain excellent properties as a container due to biaxial orientation. In addition, the tensile elastic modulus is 25,000 Kgf /
Polycarbonate (PC), polyamide (PA), polyethylene naphthalate (PEN) of about cm ²
Etc. can also be used as a preform molding resin material.

As described above, according to this embodiment, the second lip cavity mold 70 can be integrally released from the mold by driving the second injection core mold 30 in the axial direction. The second injection core mold 40 can also be integrally driven to be released at the timing when there is no interference member on the outer periphery of the undercut 18 of 20. Other transmission means may be adopted as long as they can realize the function of releasing the second injection core mold 40 after the initial movement. For example, instead of providing the stepped surface 74b and the coil spring 78, an actuator such as an air or oil cylinder may be provided between the flange 46 and the bottom wall inner surface 74a.

Next, a modified example in which the first and second core molds 30 and 40 in the above embodiment are constituted by one injection core mold 80 will be described with reference to FIGS. 3 and 4.

The injection core mold 80 shown in FIG. 3 is composed of a core pin portion 82 defining the inner wall of the body portion, a bulging portion 84 defining the inner wall of the lip portion, and a base end portion 86. on the other hand,
The second lip cavity mold 90 has a tubular portion 91 that is inserted through the base end portion 86, and also has a cavity surface 92 that defines the outer wall of the lip portion 22 of the preform 20 including the undercut 18. The base end portion 94 at the upper end of the tubular portion 91 is connected to a lifting drive source such as a cylinder. In addition, the inner surface 96 of the bottom wall of the second lip cavity mold 90 and the lower surface 84 of the base end portion 86 of the injection core mold 80.
And are connected by an actuator 98 composed of an air cylinder, an oil cylinder, or the like.

The releasing operation of the injection-molding die having such a configuration is as follows.

When the second lip cavity mold 90 is moved upward by a drive source (not shown), the upward moving force during this initial movement is absorbed by the actuator 98 and is not transmitted to the injection core mold 80.

As a result of this initial movement, as shown in FIG. 4A, a space free of any interference member is secured around the undercut 18 of the preform 20. After the initial movement in which such a space is secured, the second lip cavity mold 90 is still moved upward. Then, this upward moving force is transmitted to the injection core mold 80 via the actuator 98, and as shown in FIG. 4B, a releasing operation is realized by forcibly removing the injection core mold 80 using the elastic deformation of the undercut 18. Will be.

Also in the case of the embodiment shown in FIG. 3, instead of the actuator 98, the same function may be realized by the step surface and the spring as shown in FIG.

Next, the shape of the lip portion 22 molded by the above injection molding die will be considered.

FIG. 5A is an enlarged sectional view of the lip portion 22, and FIG. 5B is a schematic perspective view of the lip portion 22.

As shown in the figure, the lip portion 22 is
The sphere 16 is rotatably housed and held therein. The inner wall of the lip portion 22 is in contact with the sphere 16 at three points in cross section, and the wall portions in contact with each other are the first inclined wall portion 100, the vertical wall portion 102, and the second inclined wall portion 104. Is configured as.

The first inclined wall portion 100 is inclined outward toward the opening end of the lip portion 22, and is in line contact with the lower hemisphere of the spherical body 16 on the circumference. Second inclined wall portion 10
4 is formed in an undercut shape that inclines inwardly toward the opening end of the lip portion 22, and is in line contact with the upper hemisphere of the spherical body 16 on the circumference. Moreover, the thickness thereof is tapered toward the opening end. Vertical wall 102
Extends vertically by connecting the first and second inclined wall portions 100 and 104, and is in line contact on the maximum diameter line that partitions the lower hemisphere and the upper hemisphere of the sphere 16.

Further, as a feature of the second inclined wall portion 104 having an undercut shape, the slit 106 cut out from the free end portion 104a toward the base end portion 104b.
Are provided at a plurality of, for example, five locations in the circumferential direction.
The slit is formed such that the notch width becomes wider toward the free end portion 104a side, and as an example thereof, the shape of the line portion of the free end portion 104a is formed in an arc shape, and as a whole, as shown in FIG. 5B, The second inclined wall portion 104 has a petal shape that is inclined inward.

FIGS. 7A and 7B are sectional views of the injection mold for molding the lip portion 22 as described above in a clamped state. As shown in FIG. 7A, a second lip cavity 110 for molding the first inclined wall portion 100 includes a first and second injection core molds 30, 40, and an injection cavity mold 50.
It is formed between the first lip cavity mold 60 and the first lip cavity mold 60. A first lip cavity 112 for molding the second inclined wall portion 104 is formed between the second injection core mold 40 and the second lip cavity mold 70. The second lip cavity 112 has an outer edge portion 124 rather than a proximal end 122 thereof.
It has a tapered shape that tapers off toward.
A third lip cavity 114 for molding the vertical wall portion 102 is formed between the second injection core mold 40 and the first lip cavity mold 70. In the cross section including the slit 106, as shown by the contact surface 120 in FIG. 7B, the second injection core mold 40 is formed at a position corresponding to the slit 106.
And the second lip cavity mold 70 are in contact with each other. The circumferential length of the contact surface 120 is short at the base end 122 and becomes longer toward the free end or the outer edge 124. Further, the outer edge portion 124 is curved in an arc shape in the circumferential direction.

As described above, the slit 106 is formed on the side of the free end 104a of the second inclined wall portion 104, and further, the thickness is reduced toward the opening end side, so that the injection core mold is forcibly removed in the injection molding process. At this time, the elastic deformation of the second inclined wall portion 104 was extremely easily performed, and the defective molding could be significantly reduced. Moreover, the slit 106 has a larger notch width on the free end 104a side, so that the elastic deformation on the free end 104a side having a large elastic deformation amount can be ensured to be performed more smoothly. Also, this second
The free end 104a side of the inclined wall portion 104 is a portion farthest from the gate in the injection step, and if this portion is thinned, a molding defect due to a short circuit is most likely to occur. It has been confirmed that it is most effective to form the petal shape on the free end 104a side of the second inclined wall portion 104 in order to prevent such a short circuit.

[0047]

As described above, according to the injection mold of the present invention, when molding a preform having an undercut in the mouth, the outer wall of the mouth including the undercut area is defined. By driving the second lip cavity mold for releasing, a space that does not cause any interference member can be secured on the outer periphery of the undercut, and then the injection core mold is logically driven, whereby the undercut area is easily elastically deformed and molded. It is possible to realize release driving without causing defects.

Further, since it is not necessary to perform complicated processing on the injection core mold to form the undercut and the mechanical strength thereof can be secured, a highly durable mold can be provided.

Further, according to the mouth shape of the resin container according to the present invention, the mouth portion is provided with the first and second wall portions for holding the spheres rotatably accommodated therein, and the spheres are prevented from coming off. Therefore, by providing a plurality of slits in the circumferential direction on the free end side of the second wall portion having an undercut shape, elastic deformation of the undercut area at the time of mold release after injection molding is smoothly realized. be able to.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a preform injection molding die to which the present invention is applied.

FIGS. 2A and 2B are schematic cross-sectional views for explaining a mold releasing operation near the lip portion of the mold shown in FIG.

FIG. 3 is a schematic cross-sectional view showing a modified example of the injection molding die to which the present invention is applied.

4A and 4B are explanatory views for explaining a releasing operation in the vicinity of a lip portion of the injection molding die shown in FIG.

5A is a cross-sectional view of a lip portion of a resin container to which the present invention is applied, and FIG. 5B is a schematic perspective view of the lip portion.

FIG. 6 is a schematic sectional view of a roll-on type container.

7A and 7B are schematic cross-sectional views showing a clamped state of an injection mold for molding an undercut.

[Explanation of symbols]

 10 Container 12,22 Mouth 18 Undercut 20 Preform 30 First Injection Core Mold 40 Second Injection Core Mold 44 Bulging Part 50 Injection Cavity Mold 60 First Lip Cavity Mold 62a, 62b Split Mold 70, 90 Second lip cavity type 78 Coil spring 80 Injection core type 84 Bulging portion 98 Actuator 100 First inclined wall portion 102 Vertical wall portion 104 Second inclined wall portion 104a Free end portion 106 Slit

Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location B65D 1/02 A 7445-3E // B29L 22:00 4F

Claims (7)

[Claims] 1. A preform having a bottomed tubular body portion and a lip portion on the opening end side, and an undercut protruding inwardly toward the opening end side is formed on the lip portion. An injection molding die for injection molding, comprising: an injection core mold having an outer shape defining an inner wall of the lip portion and a body portion, and being moved in a longitudinal direction relative to the preform; An injection cavity mold that has a cavity surface that defines the outer wall of the part and that is moved in the longitudinal direction relative to the preform, and is arranged adjacent to the injection cavity mold when the mold is closed,
A first lip cavity mold having a cavity surface that defines an outer wall of a non-undercut area of the lip portion and configured as a pair of split molds that are respectively moved in opposite lateral axis directions; A second lip disposed adjacent to the first lip cavity mold and having a cavity surface defining an outer wall of an undercut area of the lip portion and moved in a longitudinal direction relative to the preform. At the time of releasing from the cavity mold, the initial movement for releasing the second lip cavity mold in the relative longitudinal direction was performed by the initial movement amount to secure a space around the undercut area. And a mold driving mechanism for performing relative mold-releasing movement of the injection core mold in the vertical axis direction while elastically deforming the undercut area to the outside. Injection mold that. 2. The injection core mold according to claim 1, further comprising a core pin defining an inner wall of the lip portion and a body portion, and a base end portion having an outer diameter larger than an outer diameter of the core pin. The second lip cavity mold has a cylindrical portion that is inserted into the base end portion and has a bottom wall inner surface at a position facing the base end portion of the injection core mold, and the mold drive mechanism is The second lip cavity mold is driven in the direction of the longitudinal axis, and the mold driving mechanism is arranged between the base end portion and the inner surface of the bottom wall to allow the second lip cavity mold to move during the initial movement. Injection molding, characterized in that it has transmission means for transmitting the driving force of the second lip cavity mold after the initial movement to the injection core mold without transmitting the driving force of the lip cavity mold to the injection core mold. Type. 3. The injection core mold according to claim 1, wherein the injection core mold has a core pin having an outer shape that defines the inner wall of the body portion, and the core pin is moved in the longitudinal direction relative to the preform. An injection core mold, and a second injection core mold that is arranged to be inserted through the core pin and has an outer shape that defines the inner wall of the lip portion and that is moved in the longitudinal direction relative to the preform. The mold driving mechanism includes the first injection core mold and the second injection core mold.
Is integrally driven in the longitudinal direction, and the second injection core mold is moved to the second injection core mold after the first initial movement of the first injection core mold and the second lip cavity mold. An injection molding die, characterized in that it is configured so as to perform a releasing movement integrally with the first injection core die and the second lip cavity die. 4. A bottomed tubular biaxial obtained by biaxially stretch-blow molding a lip portion formed on the opening side when a bottomed tubular preform is injection-molded and a body portion of the preform. And a lip portion for rotatably accommodating and holding a sphere. The lip portion extends outwardly toward the opening end of the lip portion and contacts the lower hemisphere of the sphere. At least a first wall portion, and a second wall portion that is formed in an undercut shape that extends inwardly toward the lip portion opening end and that contacts the upper hemisphere of the spherical body, The synthetic resin container characterized in that the second wall portion is provided with a plurality of slits cut out from the free end portion toward the base end in the circumferential direction. 5. The synthetic resin container according to claim 4, wherein the slit has a notch width that increases toward a free end side of the second wall portion. 6. The synthetic resin container according to claim 5, wherein a free end edge portion of the second wall portion surrounded by the two slits is formed in an arc shape. 7. The synthetic resin container according to claim 4, which is molded from a hard resin material having a tensile elastic modulus of 18000 Kgf / cm ² or more.