Blow molding device

A blow molding device includes a nozzle, a pressurized fluid supply source, a seal body, and a rod. The seal body includes a tubular wall. A communication depression extending from a lower end of the tubular wall to a communication port open on an outer circumferential surface of the tubular wall is provided in an inner circumferential surface of the seal body. A communication path is provided in the nozzle. The blow molding device further includes a fluid suction source configured to suck an incompressible fluid from the communication depression through the communication path and the communication port, and/or a pressurized gas supply source configured to supply a pressurized gas that blows off the incompressible fluid from the communication depression through the communication path and the communication port.

TECHNICAL FIELD

The present disclosure relates to a blow molding device.

BACKGROUND

Resin-made containers such as bottles made of polypropylene (PP) and bottles (PET bottles) made of polyethylene terephthalate (PET) are used to contain various contents including beverages, cosmetics, medicines, detergents, and toiletries such as shampoos. Such a container is typically obtained as follows: A resin-made preform formed in a bottomed tubular shape by injection molding or the like is heated to a temperature at which stretching effect can be exhibited, and, in this state, subjected to biaxial stretching blow molding using a blow molding device to be formed in a predetermined shape.

A known blow molding device uses an incompressible fluid such as a pressurized liquid instead of pressurized air, as a pressurized fluid supplied into a preform. In this case, the contents to be contained in the container as a product are used as the fluid for pressurization, so that a step of filling the container with the contents can be omitted and the production process and the structure of the blow molding device can be simplified.

For example, JP 2013-208834 A (PTL 1) describes a blow molding device that includes: a mold in which a preform can be placed; a nozzle engageable with a mouth portion of the preform; a pressurized fluid supply source capable of supplying a pressurized liquid to the nozzle; and a stretching rod movable in a vertical direction, and, while stretching the preform in a longitudinal direction (axial direction) by the stretching rod, supplies the pressurized liquid into the preform and stretches the preform in a transverse direction (radial direction) to mold the preform into a container of a shape along the cavity of the mold.

CITATION LIST

Patent Literature

SUMMARY

Technical Problem

With the conventional blow molding device described in PTL 1, when the nozzle is raised to separate from the mouth portion of the container after the blow molding, the liquid (incompressible fluid) adhering to the surface of the nozzle or the surface of the stretching rod may drip down. Particularly in the case where the incompressible fluid for blow molding is a liquid with relatively high viscosity such as a shampoo or a liquid detergent, the time for the liquid to drip down from the nozzle or the like after the blow molding is long, and also the liquid keeps dripping for a while in a drizzling manner. Hence, the liquid tends to drip onto the molded container or the mold from which the container has been removed, and adhere to the container or the mold.

It could therefore be helpful to provide a blow molding device that can, when a nozzle is separated from a mouth portion of a molded container after blow molding, prevent an incompressible fluid from dripping from the nozzle and thus prevent the fluid from adhering to the molded container or the mold.

Solution to Problem

A blow molding device according to the present disclosure comprises: a tubular nozzle; a pressurized fluid supply source configured to supply a pressurized incompressible fluid to the nozzle; a tubular seal body configured to move in a vertical direction between a closed position in which the nozzle is closed and an open position in which the nozzle is open; and a rod having an outer circumferential surface that faces an inner circumferential surface of the seal body, and configured to move in the vertical direction, wherein the seal body includes a tubular wall having an outer circumferential surface that faces the nozzle when the seal body is in the closed position, a concave communication depression extending from a lower end of the tubular wall to a communication port open on the outer circumferential surface of the tubular wall is provided in the inner circumferential surface of the seal body, a communication path that communicates with the communication port when the seal body is in the closed position is provided in the nozzle, and the blow molding device further comprises at least one of: a fluid suction source configured to suck the incompressible fluid from the communication depression through the communication path and the communication port; and a pressurized gas supply source configured to supply a pressurized gas that blows off the incompressible fluid from the communication depression through the communication path and the communication port.

Preferably, in the blow molding device according to the present disclosure, the communication depression is composed of a plurality of vertical grooves arranged at regular intervals in a circumferential direction of the tubular wall and each extending in the vertical direction, and an inner circumferential surface of the tubular wall located between the plurality of vertical grooves comes into contact with the outer circumferential surface of the rod.

Preferably, in the blow molding device according to the present disclosure, a concave outer communication depression extending from the lower end of the tubular wall to the communication port is provided in an outer circumferential surface of the seal body.

Preferably, in the blow molding device according to the present disclosure, the outer communication depression is composed of a plurality of outer vertical grooves arranged at regular intervals in a circumferential direction of the tubular wall and each extending in the vertical direction.

Advantageous Effect

It is thus possible to provide a blow molding device that can, when a nozzle is separated from a mouth portion of a molded container after blow molding, prevent an incompressible fluid from dripping from the nozzle and thus prevent the fluid from adhering to the molded container or the mold.

DETAILED DESCRIPTION

More detailed description will be given below with reference to the drawings.

Herein, the term “vertical direction” denotes an up-down direction. In one of the disclosed embodiments described below, a nozzle7, a seal body11, and a rod16have a common central axis O in the vertical direction. In this embodiment, the term “longitudinal section” denotes a section by a plane including the central axis O, and the term “cross section” denotes a section by a plane perpendicular to the central axis O. The radial direction with respect to the central axis O is also simply referred to as “radial direction”, the circumferential direction with respect to the central axis O is also simply referred to as “circumferential direction”, and the axial direction of the central axis O is also simply referred to as “axial direction”.

As illustrated inFIG. 1, a blow molding device1according to one of the disclosed embodiments is a device that blow molds a bottomed tubular preform2having a mouth portion2ainto a container C (seeFIG. 3). The blow molding device1includes a mold3in which the preform2can be placed. The mold3has a bottle-shaped cavity4(only partially illustrated in the drawing) that is open on the upper surface of the mold3. The preform2is placed in the mold3in a standing position with the mouth portion2abeing on the upper side. When the preform2is placed in the mold3, the mouth portion2aprojects upward from the cavity4. The mold3is openable right and left, and the molded container C can be taken out of the mold3by opening the mold3, although not illustrated in detail.

The preform2can be obtained, for example, by forming a thermoplastic resin material that develops stretchability as a result of heating, such as polypropylene (PP), polyethylene terephthalate (PET), or polyethylene (PE), in a bottomed tubular shape by injection molding, compression molding, extrusion molding, or the like.

A nozzle unit5is provided above the mold3so as to be movable in the vertical direction relative to the mold3. The nozzle unit5includes a main block6. The main block6is a combination of a plurality of members, although its detailed description and illustration are omitted.

The nozzle unit5includes a tubular nozzle7that can engage with the mouth portion2aof the preform2. The nozzle7has a nozzle tip7aformed in a cylindrical shape whose outer diameter is smaller than the inner diameter of the mouth portion2aof the preform2so that the lower end surface of the nozzle tip7awill abut a step portion formed on the inner surface of the mouth portion2aof the preform2. The outer diameter of the nozzle tip7amay be equal to the inner diameter of the mouth portion2aof the preform2so that the outer circumferential surface of the nozzle tip7awill abut the inner circumferential surface of the mouth portion2a. As a result of the nozzle tip7abeing inserted into the mouth portion2aof the preform2, the nozzle7can engage with the mouth portion2a. The nozzle7also has a sandwiched portion7bintegrally provided above the nozzle tip7a, and is sandwiched and fixed by the inner surface of the main block6at the sandwiched portion7b. For example, the nozzle7may be made of a steel material, a resin material, or the like.

The nozzle7is located coaxially with the cavity4of the mold3. Hence, as a result of the nozzle unit5being lowered to a predetermined position, the nozzle tip7acan be inserted into the mouth portion2aof the preform2placed in the mold3.

A supply path8extending in the vertical direction is formed inside the main block6. The supply path8is connected to the nozzle7from above. The supply path8is also connected to a pressurized fluid supply source10through a piping9. The pressurized fluid supply source10can supply an incompressible fluid pressurized to a predetermined pressure to the nozzle7through the piping9and the supply path8. That is, the pressurized fluid supply source10can supply the pressurized incompressible fluid to the preform2through the piping9, the supply path8, and the nozzle7during blow molding.

As the pressurized fluid supply source10, for example, a plunger pump is preferably used as a pressurization source. However, the pressurized fluid supply source10may have any other structure as long as it can supply the incompressible fluid pressurized to the predetermined pressure to the supply path8.

As the incompressible fluid supplied from the pressurized fluid supply source10to the nozzle7, i.e. the preform2, for example, a liquid with relatively high viscosity, such as a shampoo or a liquid detergent, may be used. In this case, the viscosity of the incompressible fluid when supplied to the preform2is preferably 10000 mPa·s or less.

A tubular seal body11for opening and closing the nozzle7is placed in the supply path8. The seal body11is movable in the vertical direction between a closed position in which the seal body11abuts the nozzle7from above and closes the nozzle7and an open position in which the seal body11separates from the nozzle7and opens the nozzle7. The seal body11includes a cylindrical shaft body (not illustrated), a cylindrical large-diameter portion11aintegrally connected to the lower end of the shaft body and having an outer diameter larger than the shaft body, and a cylindrical tubular wall11bintegrally connected to the lower end of the large-diameter portion11aand having an outer diameter smaller than the large-diameter portion11a. A downward-pointing conical inclined surface12is provided at the lower end of the large-diameter portion11a.

The seal body11is a single member made of a steel material, a resin material, or the like. Alternatively, the seal body11may be composed of a plurality of members.

A downward-pointing conical closed surface15is provided at the upper surface of the nozzle7, i.e. the upper surface of the sandwiched portion7bof the nozzle7. As a result of the seal body11moving to the closed position that is the lower stroke end and the inclined surface12provided at the lower end of the large-diameter portion11aabutting the closed surface15from above, the communication between the supply path8and the nozzle tip7acan be blocked by the seal body11to close the nozzle7. As a result of the seal body11moving upward from the closed position to the open position and the inclined surface12separating upward from the closed surface15of the nozzle7, the supply path8and the nozzle tip7acan communicate with each other to open the nozzle7. The shape of each of the inclined surface12and the closed surface15may be changed as appropriate. The nozzle7may be closed and opened by the outer circumferential surface of the tubular wall11band the inner circumferential surface of the nozzle7abutting and separating from each other.

As a result of the nozzle tip7abeing inserted into the mouth portion2aof the preform2placed in the mold3and the nozzle7being opened by the seal body11in a state in which the pressurized fluid supply source10is in operation, the pressurized incompressible fluid can be supplied from the pressurized fluid supply source10into the preform2through the nozzle7to blow mold the preform2. As a result of the nozzle7being closed by the seal body11after the blow molding, the supply of the incompressible fluid into the molded container C can be stopped.

The blow molding device1includes a rod16surrounded by the seal body11and movable in the vertical direction. In this embodiment, the rod16is used as a rod for biaxial stretching. Accordingly, the rod16is hereafter also referred to as “stretching rod16”. The stretching rod16is slidably installed in a hole formed at the axial center of the seal body11, and is movable in the axial direction, i.e. the vertical direction, relative to the seal body11. In blow molding, by moving the stretching rod16downward relative to the seal body11, the preform2placed in the mold3can be stretched inside the cavity4in the axial direction (longitudinal direction) by the stretching rod16. Thus, the blow molding device1can perform biaxial stretching blow molding on the preform2. The stretching rod16has a solid columnar shape.

The inner circumferential surface of the nozzle7(the nozzle tip7aand the sandwiched portion7b) is a cylindrical inner circumferential surface. The tubular wall11bof the seal body11has an outer circumferential surface that faces the inner circumferential surface of the nozzle7when the seal body11is in the closed position. A slight gap is provided between the outer circumferential surface of the tubular wall11band the inner circumferential surface of the nozzle7to reduce the sliding resistance therebetween. The outer circumferential surface of the tubular wall11bmay be configured to be in sliding contact with the inner circumferential surface of the nozzle7. The tubular wall11bhas its lower end flush with the lower end of the nozzle tip7awhen the seal body11is in the closed position.

The blow molding device1includes a suction mechanism to prevent the incompressible fluid from dripping from the stretching rod16, the seal body11, and the nozzle7after blow molding. The suction mechanism includes: a communication depression17provided in the inner circumferential surface of the seal body11; a communication port18open on the outer circumferential surface of the tubular wall11b; a communication path20provided in the nozzle7; and a fluid suction source22connected to the communication path20via an on-off valve21.

The communication path20is composed of eight radial passages20aarranged at regular intervals in the circumferential direction, as illustrated inFIGS. 1 and 2. Each radial passage20ahas a cylindrical inner circumferential surface shape extending in the radial direction from one end open on the inner circumferential surface of the sandwiched portion7bto the other end open on the outer circumferential surface of the sandwiched portion7b. Each radial passage20amay have a sectional shape other than circular, and may extend in a direction inclined in at least one of the axial direction and the circumferential direction with respect to the radial direction. A ring-shaped depression19concentric with the central axis O is provided in the outer circumferential surface of the sandwiched portion7b, and the other end of each radial passage20ais open to the ring-shaped depression19. The ring-shaped depression19forms a ring-shaped passage23together with the inner circumferential surface of the main block6. Thus, the other end of each radial passage20ais connected to the fluid suction source22through the ring-shaped passage23and the on-off valve21.

The concave communication depression17extending from the lower end of the tubular wall11bto the communication port18open on the outer circumferential surface of the tubular wall11bis provided in the inner circumferential surface of the seal body11. The communication depression17is composed of eight vertical grooves17aarranged at regular intervals in the circumferential direction of the tubular wall11band each extending in the vertical direction. Each vertical groove17ahas a U cross-sectional shape that is open radially inward throughout its length (the vertical direction). The cross-sectional shape of each vertical groove17ais, however, not limited to such U-shape. Moreover, each vertical groove17ais not limited to extending in the vertical direction. For example, each vertical groove17amay extend spirally about the central axis O. The inner circumferential surface of the tubular wall11blocated between the eight vertical grooves17ais configured to be in contact with the outer circumferential surface of the stretching rod16. The tubular wall11bcan thus serve to guide the stretching rod16. Alternatively, the inner circumferential surface of the tubular wall11blocated between the eight vertical grooves17amay be configured to be not in contact with the outer circumferential surface of the stretching rod16. Each vertical groove17aextends to the lower end of the tubular wall11bat its lower end. Each vertical groove17aextends to the communication port18at its upper end. The communication port18is composed of an opening18aof a cylindrical inner circumferential surface shape connected to the upper end of each of the eight vertical grooves17a. That is, the communication port18is composed of eight openings18a.

The eight sets of vertical grooves17a, openings18a, and radial passages20amay be arranged not at regular intervals in the circumferential direction. The cross-sectional areas of the vertical grooves17amay be different from each other. The number of sets of vertical grooves17a, openings18a, and radial passages20ais not limited to eight, and may be changed as appropriate. The communication port18may extend in the circumferential direction with respect to the central axis O and communicate with the plurality of vertical grooves17a. In this case, the number of vertical grooves17aand the number of radial passages20amay be different from each other. The number of radial passages20amay be one, with the on-off valve21being connected to the other end of the radial passage20a(i.e. the ring-shaped passage23is not provided). InFIGS. 1 and 2, etc., only one vertical groove17a, one opening18a, and one radial passage20aare given reference signs, for the sake of convenience.

The communication depression17is not limited to being composed of the vertical grooves17a. For example, the communication depression17may be composed of the vertical grooves17aand one or more annular grooves extending all around the central axis O. The communication depression17may be composed of an annular depression extending from the lower end of the tubular wall11bto the communication port18and also extending all around the central axis O.

The on-off valve21is preferably provided inside the nozzle unit5, but may be provided outside the nozzle unit5. The on-off valve21is a motor-operated control valve, and can be opened and closed by a control means (not illustrated). Alternatively, the on-off valve21may be, for example, a pneumatic or hydraulic control valve.

The fluid suction source22is formed by, for example, a vacuum pump, and can suck the incompressible fluid from the ring-shaped passage23and the communication path20when the on-off valve21is open. Thus, when the seal body11is in the closed position and the lower end of the stretching rod16is approximately flush with the respective lower ends of the nozzle tip7aand the tubular wall lib, the fluid suction source22can suck the incompressible fluid adhering to the lower ends of these parts through the communication depression17, the communication port18, the communication path20, and the ring-shaped passage23to prevent the incompressible fluid from dripping down.

An example of a procedure whereby the blow molding device1blow molds the preform2will be described below.

First, as illustrated inFIG. 1, the preform2is placed in the mold3in a state in which the seal body11is in the closed position to close the nozzle7. Following this, the nozzle unit5is lowered and the nozzle tip7ais inserted into the mouth portion2aof the preform2. At this time, the stretching rod16is at an origin position at which its lower end is flush with the lower end of the tubular wall11bof the seal body11.

The seal body11is then moved to the open position to open the nozzle7. After the nozzle7is opened, the pressurized incompressible fluid is supplied from the pressurized fluid supply source10into the preform2through the supply path8and the nozzle7, and the preform2undergoes blow molding (liquid blow molding) by the incompressible fluid. In the blow molding, the stretching rod16is lowered to stretch the preform2in the axial direction (longitudinal direction). By such biaxial stretching blow molding, the preform2is molded into the container C of a bottle shape along the cavity4of the mold3, as illustrated inFIG. 3.

After the blow molding is completed, the seal body11is lowered to the closed position to close the nozzle7, thus stopping the supply of the incompressible fluid. Moreover, the stretching rod16is raised to the origin position, i.e. the position at which its lower end is flush with the lower end of the tubular wall11bof the seal body11as indicated by a dashed-two dotted line inFIG. 4. The nozzle unit5is then raised to separate the nozzle tip7aupward from the mouth portion Ca of the container C, as illustrated inFIG. 4. The timing at which the stretching rod16is raised to the origin position may be before or after the nozzle tip7aseparates from the mouth portion Ca of the container C. As a result of the stretching rod16being raised and removed from the incompressible fluid inside the container C, a headspace corresponding to the volume of the removed stretching rod is formed inside the container C. The headspace may be formed by any other method. The rod16may be used not as a rod for biaxial stretching but as a rod for headspace formation.

After the completion of the blow molding, the on-off valve21is opened and the fluid suction source22starts operation, as a result of which the incompressible fluid adhering to the nozzle tip7a, the tubular wall11b, and the lower end of the stretching rod16is sucked through the communication depression17, the communication port18, the communication path20, and the ring-shaped passage23as indicated by dashed arrows inFIG. 4. When raising the stretching rod16after the blow molding, the incompressible fluid adhering to the outer circumferential surface of the stretching rod16can be directly sucked from the communication depression17provided in the inner circumferential surface of the seal body11, so that the incompressible fluid adhering to the outer circumferential surface of the stretching rod16can be sucked effectively. During this, the stretching rod16is squeezed by the seal body11, so that the incompressible fluid adhering to the outer circumferential surface of the stretching rod16can be accumulated near the upper end of the communication depression17. This also contributes to effective suction of the incompressible fluid adhering to the outer circumferential surface of the stretching rod16.

Thus, in the blow molding device1, the communication depression17extending from the lower end of the tubular wall11bto the communication port18is provided in the inner circumferential surface of the seal body11. Therefore, not only the incompressible fluid adhering to the nozzle tip7a, the tubular wall11b, and the lower end of the stretching rod16but also the incompressible fluid adhering to the outer circumferential surface of the stretching rod16can be effectively sucked by the communication depression17to prevent the incompressible fluid from dripping from the nozzle7, thus preventing the incompressible fluid from adhering to the molded container C or the mold3. Particularly in the case where the incompressible fluid is a liquid with relatively high viscosity such as a shampoo or a liquid detergent, the blow molding device1can prevent the liquid from dripping down and efficiently perform blow molding without increasing the cycle time.

After the completion of the blow molding, the stretching rod16may be raised to a position at which its lower end is flush with the upper end of the communication depression17as indicated by a solid line inFIG. 4, and, in this state, the incompressible fluid adhering to the lower end of the stretching rod16may be sucked through the communication depression17, the communication port18, and the communication path20. The timing at which the stretching rod16is raised to this position may be before or after the nozzle tip7aseparates from the mouth portion Ca of the container C. In this way, the incompressible fluid adhering to the lower end of the stretching rod16can be sucked efficiently. After sucking the incompressible fluid adhering to the lower end of the stretching rod16in this way, the stretching rod16may be lowered to the origin position, and, in this state, the incompressible fluid adhering to the nozzle tip7a, the tubular wall11b, and the lower end of the stretching rod16may be sucked through the communication depression17, the communication port18, and the communication path20. In this way, the incompressible fluid can be sucked more efficiently.

A modification of the blow molding device1will be described below.

As illustrated inFIGS. 5A and 5B, in a blow molding device1according to this modification, a nozzle7has eight vertical holes24open to the lower end of the nozzle tip7a, and three annular grooves25provided in the inner circumferential surface of the nozzle7and shaped like a ring around the central axis O. InFIGS. 5A and 5B, only one vertical hole24and one annular groove25are given reference signs, for the sake of convenience. The mold3and the preform2are not illustrated inFIG. 5A. InFIGS. 5A and 5B, the parts corresponding to those in the foregoing embodiment are given the same reference signs.

Each vertical hole24extends in the vertical direction, and is open to the radial passage20aat its upper end. The three annular grooves25are arranged in the axial direction. Each annular groove25intersects with the eight vertical holes24, and forms an opening at each intersection. The number of vertical holes24may be changed as appropriate according to the number of radial passages. The number of annular grooves25may be changed as appropriate. The annular grooves25may be omitted. The other components are the same as those in the foregoing embodiment.

With this structure, the incompressible fluid can be sucked not only from the communication depression17but also from the vertical holes24and the annular grooves25provided in the nozzle7, so that the incompressible fluid adhering to the nozzle tip7a, the tubular wall11b, and the lower end of the stretching rod16can be sucked particularly effectively.

Another modification of the blow molding device1will be described below.

As illustrated inFIGS. 6A and 6B, a blow molding device1according to this modification has a communication depression17composed of ten vertical grooves17aarranged at regular intervals in the circumferential direction of the tubular wall11band each extending in the vertical direction.

In this modification, a concave outer communication depression26extending from the lower end of the tubular wall11bto the communication port18is provided in the outer circumferential surface of the seal body11. The outer communication depression26is composed of eight outer vertical grooves arranged at regular intervals in the circumferential direction of the tubular wall11band each extending in the vertical direction. Each outer vertical groove26ahas a U cross-sectional shape that is open radially outward throughout its length (the vertical direction). The cross-sectional shape of each outer vertical groove26ais, however, not limited to such U-shape. Moreover, each outer vertical groove26ais not limited to extending in the vertical direction. For example, each outer vertical groove26amay extend spirally about the central axis O. The outer circumferential surface of the tubular wall11blocated between the eight outer vertical grooves26amay be spaced from or in contact with the inner circumferential surface of the nozzle tip7a. Each outer vertical groove26aextends to the lower end of the tubular wall11bat its lower end. Each outer vertical groove26aextends to the communication port18at its upper end.

The communication port18is composed of an annular groove18bprovided in the outer circumferential surface of the seal body11, connected to the upper end of each outer vertical groove26a, and centered at the central axis O, and an opening18aof a cylindrical inner circumferential surface shape connecting the upper end of each of the ten vertical grooves17ato the annular groove18b. In this modification, the communication path20is composed of one radial passage20a. The radial passage20ahas one end connected to the annular groove18b, and the other end connected to the on-off valve21.

InFIGS. 6A and 6B, only one vertical groove17a, one opening18a, and one outer vertical groove26aare given reference signs, for the sake of convenience. The mold3and the preform2are not illustrated inFIG. 6A.

InFIGS. 6A and 6B, the parts corresponding to those in the foregoing embodiment are given the same reference signs.

The ten sets of vertical grooves17aand openings18amay be arranged not at regular intervals in the circumferential direction. The eight outer vertical grooves26amay be arranged not at regular intervals in the circumferential direction. The cross-sectional areas of the outer vertical grooves26amay be different from each other. The number of sets of vertical grooves17aand openings18ais not limited to ten, and may be changed as appropriate. The number of outer vertical grooves26ais not limited to eight, and may be changed as appropriate. The communication port18is not limited to be composed of the annular groove18band the openings18a. In this modification, the shape of each vertical groove17amay be changed as mentioned above. The communication depression17is not limited to be composed of the vertical grooves17a, and may be changed as mentioned above.

With this structure, the incompressible fluid can be sucked not only from the communication depression17but also from the outer communication depression26provided in the outer circumferential surface of the seal body11, so that the incompressible fluid adhering to the nozzle tip7a, the tubular wall11b, and the lower end of the stretching rod16can be sucked particularly effectively.

The present disclosure is not limited to the foregoing embodiment, and various changes can be made without departing from the scope of the present disclosure.

For example, in the foregoing embodiment and its modifications, the blow molding device1includes the fluid suction source22capable of sucking the incompressible fluid from the communication depression17through the on-off valve21, the communication path20, and the communication port18. The blow molding device1may include, instead of or in addition to the fluid suction source22, a pressurized gas supply source capable of supplying a pressurized gas that blows off the incompressible fluid from the communication depression17(or the communication depression17and the outer communication depression26) through the on-off valve21, the communication path20, and the communication port18. For example, the pressurized gas supply source may be formed by a plunger pump. With this structure, not only the incompressible fluid adhering to the nozzle tip7a, the tubular wall11b, and the lower end of the rod16but also the incompressible fluid adhering to the outer circumferential surface of the rod16can be blown off from the communication depression17and dropped into the container C. Hence, the incompressible fluid can be prevented from dripping from the nozzle7, and thus prevented from adhering to the molded container C or the mold3.

In the foregoing embodiment and its modifications, the nozzle tip7aand the tubular wall11bare cylindrical. However, the nozzle tip7aand the tubular wall11bmay be tubular with a sectional shape such as polygonal or elliptic. In the case where the mouth portion2aof the preform2is cylindrical, it is preferable that the outer circumferential surface of the nozzle tip7ais cylindrical. The lower end of the tubular wall11bmay have an annular inclined surface inclined upward to the radial inner side, from its outer circumferential edge to its inner circumferential edge. For example, the lower end of the tubular wall11bmay be composed of an annular horizontal surface and an annular inclined surface located on the radial inner side of the annular horizontal surface. In such a case, the position at which the lower end of the rod16coincides with the upper end of the annular inclined surface can be set as the origin position of the rod16.

In the foregoing embodiment and its modifications, the rod16is shaped like a solid column. However, for example, the rod16may internally have a flow path connected to the pressurized fluid supply source10. In this case, the rod16may be, for example, composed of a cylindrical outer tube and a poppet valve-shaped opening/closing rod capable of opening and closing the lower end of the outer tube. A prefilling step of prefilling the preform2with the incompressible fluid through the flow path inside the rod16before the blow molding may be performed. Moreover, a suck back step of sucking the incompressible fluid from inside the blow-molded container C back to the pressurized fluid supply source10through the flow path inside the rod16may be performed. To enable discharge of air inside the preform2to the outside through the communication depression17, the communication port18, the communication path20, and the ring-shaped passage23in the prefilling step, an air discharge path that can be opened and closed may be provided in the ring-shaped passage23. In such a case where the flow path is provided in the rod16, too, the rod16may or may not be used as a rod for biaxial stretching.

In the foregoing embodiment and its modifications, the tubular wall11bis configured so that its lower end is flush with the lower end of the nozzle tip7awhen the seal body11is in the closed position. Alternatively, the tubular wall11bmay be configured so that its lower end is located higher or lower than the lower end of the nozzle tip7awhen the seal body11is in the closed position, depending on the type of the incompressible fluid and the like.

REFERENCE SIGNS LIST

10pressurized fluid supply source

22fluid suction source

26outer communication depression

O central axis

C container

Ca mouth portion