JP2002067127A - Apparatus and method for blow molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus and a method for blow molding capable of easily manufacturing a molding having high dimensional accuracy of an opening of an end with a simple constitution. SOLUTION: The apparatus for blow molding comprises a die head (4) having an openable and closable annular resin channel, a blow molding gas blowing channel (18) for blowing a blow molding gas to a parison, a mold (2) for blow molding having a cavity (2A) adjacent to the head and pressing an expanded parison, and a distal end jig (6) adjacent to an opposite side to the head (4) via the mold (2) to grasp the distal end opening of the parison from its interior and exterior. The method for blow molding is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blow molding apparatus and a blow molding method, and more particularly to a blow molding apparatus which has a simple structure and can be suitably used for producing a blow molded article having both ends opened, and an opening at both ends. The present invention relates to a blow molding method which can be suitably used for the production of blow molded articles and has a simple process.

[0002]

2. Description of the Related Art In recent years, a blow molding method has been widely used as a method for producing a relatively large, hollow resin product having a complicated shape, such as a fuel hose for an automobile and a duct for an engine. .

[0003] Since the fuel hose for the automobile and the air duct for the engine are usually connected to the fuel pipe and the air intake of the engine, it is required to finish the end opening, in other words, the joint part, with high dimensional accuracy. You.

As a blow molding method which satisfies the above requirements, for example, preparatory blow molding in which the end of a parison extruded into a mold cavity is pinched and then blow molded to form a preformed product having a predetermined diameter. Process, cutting and opening the end of the preformed product with a cutter provided inside the mold, inserting a jig for regulating the inner diameter dimension into the end opening of the preformed product, and removing the jig. A jig fixing step for fixing the end of the preform to the end portion, and a blow molding step of blowing air from the blow port provided in the jig into the preform to form a blow molded article by blow molding. A method for producing a resin hose has been proposed (Japanese Patent No. 2793608).

[0005] Alternatively, a blow molding material is preliminarily formed into a tube shape, and a core mold is inserted inside the open end of the preformed tube, and the pretube together with the core mold is formed inside the outer surface forming member. A method of manufacturing a hose in which the preformed tube is softened by overheating in an overheating process separate from the preforming process, and then the preformed tube is blow-molded (Japanese Patent Laid-Open No. Hei 6 (1994)). -71735).

[0006]

However, Japanese Patent No. 279
In the method for manufacturing a resin hose described in Japanese Patent No. 1608, as described above, in the pre-blow molding step, the end of the pre-formed parison was cut, so It was necessary to provide a cutter for cutting the end of the parison. Therefore,
There was a problem that the configuration of the mold was complicated.

In the method of manufacturing a hose described in Japanese Patent Application Laid-Open No. Hei 6-71735, a preformed tube previously formed by an extrusion method or the like is reheated and blow-molded, so that energy consumption is reduced. There were many problems and the process became complicated.

According to the present invention, there is provided a blow molding apparatus which can easily produce a molded product having a high dimensional accuracy at a terminal opening, and which does not require any of a cutting opening at a parison end after preforming and a preforming step. It is intended to provide a blow molding method.

[0009]

The invention according to claim 1 has an annular resin flow path formed to be openable and closable,
A die head section that forms a cylindrical parison by extruding molten resin through the annular resin flow path, and a blow molding gas blowing flow path that blows blow molding gas into the parison formed in the die head section to expand the barison. A blow molding die having a cavity portion in which the varison which is adjacent to a side of the die head portion where the annular resin flow path is opened, is subjected to mold matching, and is blown with a blow molding gas and expanded is pressed. A tip jig is provided adjacent to the opposite side of the die head portion with respect to the blow molding die, and grips a tip opening of a parison formed in the die head portion from outside and inside. The present invention relates to a blow molding device.

In the blow molding apparatus, in the die head portion, the molten resin is extruded through the annular resin flow path to form a cylindrical parison, and the front end opening of the parison is formed inside and outside by the front end jig. Then, after closing the annular resin flow path in the die head portion and matching the blow molding die, blow molding gas is blown into the parison from the blow molding gas blowing flow path. The parison is blow molded to obtain a blow molded product.

As a result, it is possible to manufacture a blow-molded product having high dimensional accuracy, particularly high dimensional accuracy in the openings at both ends and in the vicinity thereof.

In the blow molding apparatus, since the openings at both ends of the blow molded article are formed by the die head and the tip jig, the construction is simple because a cutter for cutting the tip of the parison is unnecessary. Furthermore, since the parison formed in the die head portion can be blow-molded without cooling, energy can be largely saved and productivity can be greatly improved.

According to a second aspect of the present invention, the tip jig is provided so as to surround a plug portion inserted into the tip opening of the parison, and the plug portion. The present invention relates to a blow molding apparatus including a parison gripping member gripping from the outside.

In the blow molding apparatus, the opening of the tip of the parison is gripped from the inside and the outside by the plug part and the parison holding member provided in the tip jig.

According to a third aspect of the present invention, the die head portion includes a molten resin flow path through which the molten resin is extruded, and a direction in which the molten resin is extruded and a direction opposite to the extruded direction. A mandrel movably disposed in the direction of, the annular resin flow path is formed between the wall surface of the molten resin flow path and the mandrel,
In addition, the present invention relates to a blow molding device that closes when the mandrel moves in the extrusion direction or a direction opposite to the extrusion direction.

In the blow molding apparatus, the molten resin is extruded from between the wall surface of the molten resin flow path and the mandrel to form a cylindrical parison. And
When the mandrel moves in the extrusion direction or a direction opposite to the extrusion direction and contacts the wall surface of the molten resin flow path, the annular resin flow path is closed.

Therefore, in the blow molding apparatus, when a parison of a predetermined length is formed, the mandrel can be moved to close the annular resin flow path, and blow molding can be performed.

According to a fourth aspect of the present invention, there is provided a parison forming step of extruding molten resin from a die head portion having an annular resin flow path formed so as to be openable and closable to form a cylindrical parison; A parison gripping step of gripping the opened end of the parison from the inside and the outside, closing the annular resin flow path in the die head portion, matching a blow molding die, and blowing a blow molding gas into the parison. Blow-expanding the parison, and pressing the parison against the cavity of the blow-molding mold.

According to the blow molding method, the openings at both ends of the blow molded product are formed in the parison forming step and the parison gripping step. Not only is it particularly expensive, but there is no need for a step of cutting off the tip of the parison before blow molding, and furthermore, blow molding can be performed without cooling the parison, thereby greatly saving energy.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION First Embodiment FIG. 1 shows an example of a blow molding apparatus according to the present invention.

As shown in FIG. 1, a blow molding apparatus 200
Is a die head 4 that extrudes a molten resin to form a cylindrical parison, and is adjacent to the die head 4 and
At the time of blow molding, the blow molding die 2 having a cavity 2A inside which the parison expanded by blowing compressed air is pressed, and the die head portion 4 of the blow molding die 2 are adjacent to the opposite side, A tip jig 6 for gripping the tip opening of the parison from inside and outside is provided.

As shown in FIG. 1, one end of the die head 4 is connected to an extruder (not shown) for extruding the molten resin, and a molten resin flow through which the molten resin extruded from the extruder passes. A die head main body 8 having a passage 8A formed at a central portion thereof, and a plate-shaped die head tip portion 10 detachably provided on an end surface of the die head main body 8 opposite to a side connected to the extruder.

As shown in FIG. 1, the inner wall surface of the molten resin flow path 8A is formed in a substantially cylindrical shape, and in the vicinity of the end face of the die head body 8 on the side of the die head tip 10, the direction toward the die head tip 10, that is, It expands conically downward in FIG.

At the center of the die head tip 10, a tip opening 10A having a wall surface continuous with the molten resin flow path 8A is provided.
Are formed. The wall surface of the distal end opening 10A is formed in a conical shape spreading downward and continuous with the wall surface of the molten resin flow path 8A, and is formed in a cylindrical shape at the lower end in FIG. The molten resin flow path in the blow molding apparatus of the present invention is formed by the molten resin flow path 8A and the tip opening 10A.

The molten resin flow path 8A and the tip opening 10A
The mandrel 12 is accommodated in the space defined by the above as shown in FIG.

The mandrel 12 has a conical surface having the same gradient as the conical surface of the molten resin flow path 8A and the tip opening 10A, and an outer peripheral surface formed of a cylindrical surface continuing below the conical surface. A disk-shaped mandrel main body 12A housed in a space formed by the molten resin flow path 8A and the front end opening 10A, and a mandrel pushing rod 12B erected at the center of the upper surface of the mandrel main body 12A. It has.

The mandrel 12 is formed so as to be movable in the direction of extruding the molten resin and in a direction opposite to the direction of extrusion a. , And an open position where a gap is formed between the outer peripheral surface of the mandrel main body 12A and the wall surfaces of the molten resin flow path 8A and the distal end opening 10A. The positional relationship between the mandrel main body 12A, the molten resin flow path 8A, and the wall surface of the distal end opening 10A shown in FIG. 1 is a positional relationship when the mandrel 12 is at the closed position. FIG. 2 shows a positional relationship between the mandrel main body 12A, the molten resin flow path 8A, and the wall surface of the distal end opening 10A when the mandrel 12 is at the open position.

When the mandrel 12 is in the closed position, as shown in FIG. 1, the outer peripheral surface of the mandrel main body 12A has a conical surface with a conical portion on the wall surface of the molten resin flow path 8A and the tip opening 10A. , And the annular resin flow path 4A is closed. And the mandrel body 12A
A cylindrical space is formed between the cylindrical surface portion on the outer peripheral surface of the device and the cylindrical surface portion on the wall surface of the distal end opening 10A. When the mandrel 12 is closed after forming the parison in the die head 4, the base of the parison, that is, the vicinity of the die head 4 is firmly held in the space.

On the other hand, when the mandrel 12 is in the open position, as shown in FIG. 2, an annular resin flow path 4A is formed between the mandrel 12 and the wall surface of the molten resin flow path 8A and the end opening 10A. You.

FIG. 1 and FIG.
As shown in (1), it is formed so as to be divided into two parts along a center line parallel to the extrusion direction a of the molten resin. 1 and 2 show the die head tip 1.
The state where the two parts at 0 are combined into one is shown.

As shown in FIGS. 1 and 2, the blow molding die 2 is formed adjacent to the die head portion 4 and can be divided into two portions along a center line parallel to the extrusion direction a. ing. A cavity 2 </ b> A is formed on the inside to press the parison at the time of blow molding. The cavity 2A is formed so as to be continuous with the inner wall surface of the tip opening 10A at the upper end, that is, the end on the die head 4 side, and has a conical surface whose lower end is reduced downward.

As shown in FIGS. 1 and 2, the tip jig 6 has a cylindrical plug portion 14 whose tip portion is located inside the cavity 2A of the blow mold 2 during blow molding, And a parison gripping member 16 having a cylindrical inner wall surface facing the outer peripheral surface of the plug portion 14, and a base portion 20 on which the plug portion 14 and the parison gripping member 16 are placed. Prepare. The base 20 is formed so as to be able to ascend and descend.

The plug portion 14 is provided with a compressed air blowing hole 18 for blowing compressed air into the parison at the time of blow molding along the axis. Compressed air blow hole 18
Corresponds to the blow molding gas blowing passage in the blow molding apparatus of the present invention, and compressed air is an example of the blow molding gas in the present invention. In addition, nitrogen gas or the like can be used as the blow molding gas.

The parison gripping member 16 is formed so as to be dividable into two parts along a center line parallel to the extrusion direction a of the molten resin, similarly to the blow molding die 2. Each is formed so as to be movable both in a direction approaching the plug portion 14 and in a direction away from the plug portion 14.
At the time of blow molding, as shown in FIGS. 1 and 2, the two portions move in a direction approaching the plug portion 14 and unite to form one parison gripping member 16.
Then, in cooperation with the plug portion 14, the tip opening of the parison is gripped from inside and outside.

FIG. 3 shows an example of a blow molding method using the blow molding apparatus according to the first embodiment.

In FIG. 3, (A), (B), (C),
And (D) respectively show a parison forming step, a parison gripping step, a blow molding step, and a blow molded article removal step. (E) shows the blow-molded product taken out in the blow-molded product take-out step (D).

As shown in FIG. 3A, in the parison forming step (A), since the blow molding die 2 is in the open state and the mandrel 12 is in the open position, the mandrel 12 and the molten resin flow Road 8A and tip opening 10
An annular resin flow path 4 </ b> A is formed between A and A. .

When the molten resin is extruded from the extruder in the above state, the molten resin is extruded through the annular resin flow path 4A into a cylindrical shape downward in FIG. 3 to form a cylindrical parison P.

When the lower end of the parison P comes into contact with the base 20 of the gripping member 6, the parison gripping member 16 is brought close to the plug portion 14 as shown in FIG. That is, the tip opening is kept airtight from inside and outside.

Next, the mandrel 12 is moved upward to the closed position as shown in FIG.
Close. In the above state, the base of the parison P is hermetically held in a cylindrical space between the inner wall surface of the tip opening 10A at the die head tip 10 and the outer peripheral surface of the mandrel body 12A. , At the root portion and at the tip opening.

After closing the annular resin flow path 4A, the blow molding die 2 is closed and compressed air is blown into the parison P through the compressed air blowing hole 18. As a result, the parison P expands outward and is pressed against the cavity 2A, and at the same time, a joint is formed between the root portion and the distal end opening of the parison P, and the blow molded product M is obtained.

When the blow molding is completed, as shown in FIG. 3D, the blow molding die 2, the die head tip 10, and the parison gripping member 16 are opened, and the base 20 of the tip jig 6 is lowered. Then, the blow molded product M is taken out.

In the blow molding apparatus according to the first embodiment, as described above, during the blow molding, the parison P
At the root, the die head tip 10 and the mandrel body 12A are firmly held by the parison gripping member 16 and the plug 14 at the tip opening, so that joints at both ends of the blow molded product M are formed.

Therefore, the blow molding apparatus does not require a cutter for cutting the end of the parison P before or after the blow molding, so that the blow molding apparatus has a simple structure. Moreover, the obtained blow molded product M is
High dimensional accuracy, especially at the joints at both ends.

In the blow molding apparatus, since the blow molding can be performed without cooling the parison P, the process can be shortened and energy can be saved.

In addition, one or both of the die head tip 10 and the mandrel 12 are replaced to change the inner diameter of the tip opening 10A, the distance between the tip opening 10A and the mandrel 12, and the diameter of the mandrel 12. By changing at least one of the parisons P, the thickness, inner diameter, and outer diameter of the parison P can be adjusted.

Therefore, the blow molding apparatus can be suitably used for blow molding of high-precision products such as so-called high-tech blow-molded products, such as automotive fuel hoses and engine air ducts.

2. Second Embodiment Another example of the blow molding apparatus according to the present invention is shown in FIG. 4, the same reference numerals as those in FIGS. 1 to 3 indicate the same elements as those shown in FIGS. 1 to 3 unless otherwise specified.

As shown in FIG. 4, in the blow molding apparatus 202 according to the second embodiment, the plug portion 14 does not have an air blowing hole, and the mandrel 12 is provided with a compressed air blowing hole 22 instead. During blow molding, compressed air is blown into the parison P through the compressed air blowing holes 22. Note that the compressed air blowing hole 22 also corresponds to a blow molding gas blowing passage in the blow molding device of the present invention.

The blow molding apparatus 202 has the same configuration as the blow molding apparatus shown in FIGS. 1 and 2 except for the above-mentioned points.

When blow molding is performed using the blow molding apparatus 202, a blow molded product can be manufactured according to a procedure similar to the procedure shown in FIG.

The blow molding apparatus according to the second embodiment is
In addition to the features of the blow molding apparatus according to the first embodiment, there is no need to provide a compressed air blowing hole and a compressed air supply pipe for supplying compressed air to the plug portion 14 of the tip jig 6. It has the feature that the configuration of the jig 6 can be further simplified.

3. Third Embodiment Still another example of the blow molding apparatus according to the present invention is shown in FIG. In FIG. 5, the same reference numerals as those in FIGS. 1 to 3 indicate the same components as those shown in FIGS. 1 to 3 unless otherwise specified.

As shown in FIG. 3, the blow molding apparatus 204 according to the third embodiment also has a die head 4 and a blow head similar to the blow molding apparatuses according to the first and second embodiments.
A blow molding die 2 and a tip jig 6 are provided.

As shown in FIG. 5, the blow molding device 204
The die head portion 4 accommodates the mandrel 28 therein and has a molten resin flow path 24 through which the molten resin flows.
A includes a die head main body 24 in which A is formed, and a die head tip portion 26 which is a plate-shaped member fixed to an end surface of the die head main body 24. At the center of the die head tip 26, there is an inner wall surface which is continuous with the inner wall surface of the molten resin flow path 24A. A portion 26A is formed.

In the molten resin flow path 24A, a mandrel accommodating chamber 24B for accommodating a mandrel is formed at a tip portion, that is, a portion near the die head tip portion 26. The mandrel accommodating chamber 24B has an enlarged portion whose inner diameter expands conically toward the distal end portion, a reduced portion located closer to the distal end side than the enlarged portion, and whose inner diameter decreases conically toward the distal end portion, A parallel portion having a constant inner diameter is formed between the enlarged portion and the reduced portion.

The inner wall surface of the distal end opening 26A is also formed in a conical surface continuous with the reduced portion of the molten resin flow path 24A, and a parallel portion having a cylindrical inner wall surface is formed at the lower end. I have.

As shown in FIG. 5, the mandrel 28 includes a rod 28B inserted into the molten resin flow path 24A, and a mandrel main body 28A which is a substantially spindle-shaped expansion part formed at the tip of the rod 28B. Is provided. Mandrel body 28
A is an enlarged portion whose outer diameter increases conically toward the tip of the mandrel 28, and is formed closer to the distal end of the mandrel 28 than the enlarged portion, and the outer diameter decreases conically toward the distal end. It has a reduced portion and a parallel portion located between the enlarged portion and the reduced portion and having a cylindrical outer wall surface, and a column-shaped projection is formed at the tip. The reduced portion of the mandrel main body 28A corresponds to the molten resin flow path 24A.
Are formed so as to have the same gradient as the reduced portion in FIG.

As shown by the solid line in FIG. 5, the mandrel 28 has an open position where a fixed space is formed between the reduced portion of the mandrel main body 28A and the reduced portion of the molten resin flow path 24A and the tip opening 26A. As shown by the two-dot chain line in FIG. 5, the reduced portion of the mandrel main body 28A is formed by the molten resin flow path 24A and the tip opening 26A.
Is formed so as to be held at any one of a closed position and an abutting position on the reduced portion.

When the mandrel 28 is at the open position, an annular resin flow path 4A is formed between the mandrel 28, the molten resin flow path 24A and the tip opening 26A, and the cylindrical protruding portion of the mandrel main body 28A. When,
A cylindrical space is formed between the tip opening 26A and the parallel portion. The cylindrical space has an annular resin flow path 4A.
And can be rephrased as die orifice 4B.

On the other hand, when the mandrel 28 is at the closed position, the annular resin flow path 4A is closed.

At the center of the mandrel 28, a compressed air blowing hole 30 for blowing compressed air into the parison at the time of blow molding is provided. The compressed air blowing hole 30 corresponds to a blow molding gas blowing passage in the blow molding device of the present invention.

The blow molding die 2 of the blow molding apparatus 204 has the same structure as that shown in FIGS. 1 to 4 except that the cavity 2A is formed at the upper end so as to be continuous with the parallel portion at the tip opening 26A. It has the same configuration as the blow molding die 2 in the molding devices 200 and 202. The tip jig 6 is formed similarly to the tip jig 6 in the blow molding apparatus 202 shown in FIG.

In the blow molding device 204, blow molding can be performed according to the following procedure.

First, the mandrel 28 is held in the open position,
The molten resin is extruded from an extruder connected to the die head 4. The molten resin passes through the annular resin flow path 4A and is extruded from the die orifice 4B between the mandrel main body 28A and the tip opening 26A to form a cylindrical parison. As shown in FIG. 5, the cross-sectional area of the cavity 2A of the blow molding die 2 along a plane perpendicular to the direction of extruding the molten resin a is larger than the cross-sectional area of the die orifice 4B along the plane. When the parison is much larger, the parison does not hit the inner wall surface of the cavity 2A in the blow mold 2, so that it is not necessary to open the blow mold 2 during the parison formation.

After the parison is formed, the tip opening of the parison is gripped from the inside and the outside by the tip jig 6 in the same manner as in the blow molding devices 200 and 202, and the mandrel 28 is lowered to hold it in the closed position. Then, the annular resin flow path 4A is closed. And compressed air blowing hole 3
From 0, compressed air is blown into the parison to expand the parison and press it against the cavity 2A to perform blow molding.

After the blow molding, the die head end portion 26, the blow molding die 2, and the parison gripping member 16 are opened to take out the blow molded product.

The blow molding apparatus 204 according to the third embodiment
Has the same features as the blow molding apparatus according to the first and second embodiments.

Further, when molding a blow molded product having a small outer and inner diameter of the joint, it is necessary to reduce the inner and outer diameters of the die orifice 4B. 28A
The outer diameter of the protruding portion and the inner diameter of the parallel portion at the distal end opening 26A may be reduced, so that the structure of the blow molding apparatus used for molding a blow molded product having a small outer diameter and inner diameter of the joint portion is also reduced. No overkill occurs.

[0070]

According to the present invention, a blow-molded product having high dimensional accuracy at the openings at both ends can be easily manufactured, and further, the cutting opening at the end of the parison after the preforming and the preforming step are unnecessary. A blow molding method and a blow molding apparatus that can be preferably used in the blow molding method are provided.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an example of a blow molding apparatus according to the present invention.

FIG. 2 shows a blow molding apparatus shown in FIG.
It is a longitudinal cross-sectional view showing the state where the annular resin flow path was opened.

FIG. 3 is a process chart showing an example of a blow molding method using the blow molding apparatus shown in FIGS. 1 and 2.

FIG. 4 is a longitudinal sectional view showing another example of the blow molding apparatus according to the present invention.

FIG. 5 is a longitudinal sectional view showing still another example of the blow molding apparatus according to the present invention.

[Explanation of symbols]

2 Blow mold 4 Die head 4A Annular resin flow path 6 Tip jig 8A Molten resin flow path (Molten resin flow path) 10A Tip opening (Molten resin flow path) 12 Mandrel 14 Plug section 16 Parison gripping member 18 Compressed air blowing Hole (flow molding gas injection passage) 22 Compressed air injection hole (blow molding gas injection passage) 24A Melt resin flow passage 26A Tip opening 28 mandrel 30 Compressed air injection hole (blow molding gas injection passage)

Continued on the front page (72) Inventor Hiroshi Koyama 1-1-1 Toyota-cho, Kariya-shi, Aichi F-term in Toyota Boshoku Corporation (reference) 4F208 AG07 AG23 LA01 LA07 LB01 LG04 LG22

Claims (4)

[Claims] 1. A die head having a tubular parison having a ring-shaped annular resin flow path formed to be openable and closable, and extruding molten resin through the ring-shaped resin flow path; A blow molding gas blowing flow path for blowing the blow molding gas into the parison and expanding the varison, a blow molding gas which is adjacent to a side of the die head portion where the annular resin flow path is opened, and is subjected to mold matching. A blow molding die having a cavity portion against which the blown and expanded barison is pressed, and the die head portion is adjacent to the die head portion across the blow molding die, and at the time of the blow molding, in the die head portion, A tip jig for gripping a tip opening of the formed parison from outside and inside. Shaped device. 2. The parison gripping member, wherein the tip jig is provided so as to surround a plug inserted into a tip opening of the parison and the plug, and grips the tip opening of the parison from outside. The blow molding apparatus according to claim 1, comprising: 3. The molten resin flow path through which the molten resin is extruded, and a die head portion movably disposed inside the molten resin flow path in a direction in which the molten resin is extruded and in a direction opposite to the extruded direction. An annular mandrel, wherein the annular resin flow path is formed between a wall surface of the molten resin flow path and the mandrel, and the mandrel moves in the extrusion direction or in a direction opposite to the extrusion direction. The blow molding apparatus according to claim 1, wherein the blow molding apparatus is closed by performing the operation. 4. A parison forming step of extruding molten resin from a die head portion having an annular resin flow path formed to be openable and closable to form a cylindrical parison, and a tip of the parison formed in the parison forming step A parison gripping step of gripping the opening from inside and outside, and closing the annular resin flow path in the die head,
A blow molding step of matching a blow molding die and blowing blow molding gas into the parison to expand the parison and press against a cavity of the blow molding die.