JPH05212776A - Manufacture of blow molded form having opening and molded form thereof - Google Patents

Abstract

PURPOSE:To form a communicating hole without generating cutting chips in manufacturing an air duct by a method wherein an opening is formed by injection molding by regulating a boundary surface of a main cavity and an auxiliary cavity with an auxiliary mold section and other molded body is formed by blow molding so as to be integrated with the molded body at the opening. CONSTITUTION:In a main cavity 2 of a metal mold 1, an auxiliary mold section 9 forming a boundary surface of an auxiliary cavity 3 and the main cavity 2 is set so as to form the auxiliary cavity 3. A core 4 is arranged in the auxiliary cavity 3 so as to form an injection molded body 15 by an injection molding machine. The auxiliary mold section 9 is removed, a parison 11 is pushed out into the main cavity 2 from a blow molding machine 13 and a moving mold 8 is closed. Both ends of the parison 11 are pinched and air is blown in from a blow pin 12 for blow molding and the injection molded body 15 is integrated with a blow molded body 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a blow molded product having an opening on the side surface side of a blow molded product used for an air duct, a filler hose and the like, and a molded product thereof.

[0002]

2. Description of the Related Art Conventionally, a blow-molded product comprising an injection-molded opening for communicating an internal space with the outside and a blow-molded main body integrally joined to the opening is a molded body. It is formed by molding and fusing a body and a molded body having an opening in a mold (PTC WO89 / 04755 specification). However, in this method, a resin wall exists on the joint surface of the fusion-molded and molded product, and no hole communicating between the internal space and the outside is formed between the main body and the opening. Therefore, it is necessary for the molded product molded by the above-mentioned method to communicate with each other by forming a hole that communicates in the post-processing from the opening side. However, in this drilling process, since the resin wall is drilled with a drill or the like, chips and the like generated during the process may adhere to the resin wall and may not be sufficiently removed, and may remain in the molded product.
Therefore, when this molded product is used, the chips remaining inside may enter other parts and cause a problem.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and fusion-bonds an injection-molded body and a blow-molded body in a mold, and cuts holes communicating with the joint boundary surface. It is an object of the present invention to form a blow-molded article having an opening by forming the blow-molded article.

[0004]

According to the first aspect of the present invention, there is provided a method for manufacturing a blow-molded article having an opening, wherein an injection-molded opening communicating an internal space with the outside and a blower integrally joined to the opening. A blower with an opening consisting of a molded body
A method for manufacturing a molded article, comprising: a base cavity portion having a main cavity forming an outer peripheral surface of a main body portion, a sub-cavity communicating with the main cavity portion and forming an outer peripheral surface of an opening, and a base die portion of the base die portion. At least one of the sub-cavities is formed by using a molding die including a sub-mold portion that defines the boundary of the sub-cavity and a core portion that is held in the base portion so as to be relatively movable in the axial direction and forms a hole for the opening. An injection molding process in which a part boundary is defined by a sub-mold part to injection-mold a resin to form an injection-molded body of an opening, and the sub-mold part is removed from the injection-molded body, and then a parison is introduced into the main cavity. A blow molding step of blowing air into the parison to bring it into contact with the injection molded body and form a blow molded body constituting the main body, and to form a hole in the wall surface of the blow molded body Forming communication holes that connect the space to the outside And the extent, characterized in that it consists of.

A method of manufacturing a blow-molded article having an opening according to the second aspect of the present invention has a main cavity forming the outer peripheral surface of the main body and a sub-cavity communicating with the main cavity and forming the outer peripheral surface of the opening. Blow molding using a molding die composed of a base portion and a core portion forming a hole of an opening, introducing a parison into a main cavity of the base portion, and blowing air into the parison to form a main body portion. A blow molding step of forming a body, and a step of forming a hole in the wall surface of the blow molded body by relatively moving the core portion in the axial direction after the blow molding to form a communication hole for communicating the internal space with the outside; While the core portion is arranged in the sub-cavity, a resin is injection-molded in the sub-cavity and abutted and joined to the blow-molded body,
It is characterized in that any one of an injection molding step of forming an injection molded body forming an opening integrated with a blow molded body is performed first, and then another step is performed.

A blow-molded article having an opening according to the third aspect of the present invention is integrally joined to the injection-molded opening and the blow-molded opening for communicating the internal space with the outside, and An opening that communicates the internal space with the outside formed by cutting the tubular portion of the blow-molded product with a cutter, which is composed of a main body having a tubular portion that forms a central hole protruding into the internal space It is characterized by having.

In the manufacturing method of the first aspect of the present invention, the injection molded body is molded first, and then the blow molded body is molded and bonded, and at the same time, the hole for communication is formed in the wall surface of the bonding boundary at the core portion. .. The communication hole may be formed by directly forming a through hole in the core portion, or by forming a tubular member for cutting and removing in the main body portion in the core portion and then removing it with a cutter. As the cutter, knife, scissors, heating cutter, ultrasonic cutter,
A laser cutter or the like can be used.

In this injection molding process, a sub-mold portion that defines the boundary between the sub-cavity and the main cavity is provided in the main cavity of the molding die, and the resin is injection-molded in the sub-cavity in which the core portion is provided. Mold an injection molded body. In the blow molding process, the sub mold part is removed or housed in the mold to expose the end surface of the injection molded body into the main cavity, and the parison is extruded from the extruder into the main cavity and blown to blow molding the body. The injection molded bodies are brought into contact with each other and joined. At this time, the position of the core part is the same as that at the time of injection molding,
Further, it may be a position further protruding into the main cavity.
In the case of the projecting position, the blow-molded main body part is formed with a cylindrical part projecting inward.

In the communicating hole forming step, the core portion is axially driven before the wall surface of the blow-molded body is solidified, and the wall surface is crushed by the tip end face of the core portion to form a hole for communicating the internal space with the outside. May be. When the wall of the blow-molded body is formed in a soft state before the wall surface of the blow-molded body is solidified, the hole having the predetermined shape can be easily formed.

Further, in the case where the tip end face of the core portion is projected to form the tubular portion on the blow-molded body, after the blow-molded body is solidified, the tubular portion may be cut and removed by a cutter at the time of finishing. Good. Cutting with a cutter does not generate chips and the inner opening edge surface of the main body is more beautifully finished, and a high-quality blow-molded product can be obtained. The second invention is a manufacturing method in the case where a blow molded product is first molded and then an injection molded product is molded and joined.

As the molding die, a base mold portion having a main cavity forming the outer peripheral surface of the main body portion, a sub-cavity communicating with the main cavity and forming the outer peripheral surface of the opening portion, and a hole of the opening portion are formed. A mold with a core can be used. In the blow molding process, the state where the boundary with the sub-cavity of the base mold is kept communicating, the state where the boundary with the sub-cavity of the base mold is restricted only by the core part, and the sub-core part is used together with the core part. A parison is introduced into the main cavity in a state where the boundary is cut off and blow-molded to form a blow-molded body. At the time of this blow molding, even if there is some space at the boundary of the base mold portion with the sub-cavity, the air pressure of the blow is low and therefore does not affect the formation of the main body portion to be blow molded.

In this step, the core portion may be projected into the main cavity to form a tubular portion at the tip of the core portion. In the injection molding process, the resin is injection-molded to form an injection-molded body with the wall surface of the blow-molded body as the boundary surface of the sub-cavity and the core portion being in contact with or pushed into the wall surface of the blow-molded body. Therefore, the injection-molded body is brought into contact with the body-side end surface, which is a blow-molded body, and fusion-bonded.

The communicating hole forming step can be performed by press-fitting the core portion into the main cavity and breaking through the wall surface of the main body portion, or by cutting the tubular portion with a cutter, as in the first manufacturing method. .. It is possible to form a blow-molded product having a similar opening regardless of which of the communication hole forming step and the injection molding step is performed first.

Since the injection-molded resin is melted, the blow-molded product can be easily fused even if the blow-molded product is solidified to some extent if the resin is compatible. Since the blow-molded body and the injection-molded body are fused to each other, it is desirable to use a resin having a good compatibility, for example, the same kind of resin.
Also, this opening can be formed at a plurality of locations.

[0015]

According to the manufacturing method of the present invention, the boundary surface between the main cavity and the sub-cavity of the base mold portion of the molding die is regulated by the sub-mold portion or the blow molded body to mold one molded body, and then the other molded body is molded. By molding the molded body, it is possible to join it at the boundary surface to form an integrated molded product. Then, at the boundary surface of the molded body, the core is driven in the axial direction and relatively moves to open a hole before the wall surface of the blow molded body is solidified, or by providing a tubular portion and removing the tubular portion with a cutter. A hole in which the internal space communicates with the outside can be easily formed without chips.

[0016]

EXAMPLES The present invention will be specifically described below with reference to examples. FIG. 1 shows a side view of the mold used in this example, and FIG. 2 shows a schematic view of a cavity on the split mold surface. This mold 1 can be divided into two parts with the center surface of the main cavity 2 forming the blow-molded body as a dividing surface 7, and the parison 11 is provided at both ends of each dividing mold surface 7.
A movable mold part 8 for pinching both ends of the movable mold part 8 is provided. A sub-cavity 3 that forms an injection-molded body around the split mold surface 7 and a core portion 4 that is inserted into the sub-cavity 3.
And a drive unit 5 (not shown) that is connected to the core unit 4 and that can move the core unit 4 in the radial direction. A spool runner 6 is formed on the split mold surface 7 so as to be easily demolded when the mold is opened through a gate port communicating with the sub-cavity 3. Then, the nozzle of the injection molding machine 14 contacts the tip of the spool runner 6.

When the injection molding is performed first, the sub mold portion 9 that forms the boundary surface of the sub cavity 3 in the main cavity 2 is formed.
Are arranged as shown in FIG. The resin material used for molding is
Polypropylene resin containing 40% talc for blow molding (TX1088 manufactured by Mitsubishi Yuka Co., Ltd.) and polypropylene resin for injection molding (BC manufactured by Mitsubishi Yuka Co., Ltd.)
2) was used. (Embodiment 1) Here, the manufacturing method of the first invention will be described with reference to FIGS. (Injection molding step) As shown in FIG. 3, the sub-cavity 3 is formed by setting the sub-mold portion 9 that forms the boundary surface between the sub-cavity 3 and the main cavity 2 in the main cavity 2 of the mold. The core 4 is arranged inside the sub-cavity 3, and the molded body formed in the sub-cavity 3 has a through hole. An injection molding machine (not shown) 14 passes through the sprue runner 6 and a cylindrical injection molding body 15 as shown in FIG.
To mold. Next, as shown in FIG. 5, when the sub-mold portion 9 is removed, the injection molded body 15 is molded by the wall surface of the main cavity 2 so as to be restricted and projected. (Blow Molding Step) In this step, the parison 11 is extruded into the main cavity 2 from the blow molding machine 13 as shown in FIG. Next, the movable mold 8 is closed, both ends of the parison 11 are pinched, air is blown from the blow pins 12, and blow molding is performed to join the blow molded body 16 to the injection molded body 15 as shown in FIG. (Communication hole forming step) Blow molded body 16 and injection molded body 15
At the time of joining, the core portion 4 is axially driven to break through the resin wall of the blow molded body 16 to form a hole communicating with the hollow hole of the injection molded body 15, and the resin is solidified in this state as shown in FIG. Let

After the resin has solidified, the molded product is removed from the mold 1 and the spool runner 6 and the like are removed, whereby a blow molded product having an opening formed with a hole communicating the internal space with the outside is obtained. Was obtained. This blow-molded product does not require drilling or the like for post-processing. (Example 2) In this example, a blow-molded body is first formed by the manufacturing method of the second invention, and then an injection-molded body is formed and joined.

The mold used is the mold used in Example 1 except that the sub-mold portion 9 used in Example 1 is not used. (Blow molding step) As shown in FIG. 9, the end face of the core portion 4 is positioned at the boundary between the main cavity 2 and the sub cavity 3, the parison 11 is extruded, and then the movable die 8 is closed to fix both ends of the parison 11 to each other. Pinch, blow air to blow mold. (Communication Hole Forming Step) As shown in FIG. 10, the core portion 4 is axially driven to break through the wall surface of the blow-molded body 16 to form a hole for communication to the external space. (Injection molding step) Next, resin is injected into the sub-cavity 3 from the injection molding machine 14 via the spool runner 6 for molding. At this time, the injection-molded body 15 is joined and fused at the boundary surface of the blow-molded body 16 to form the same blow-molded article as in Example 1 as shown in FIG. The solidified molded product was demolded to obtain a blow molded product having an opening having a hole communicating with the joint wall surface as in the case of Example 1.

When the air blowing during blow molding is weak and strong, or when the viscosity of the parison is high, the parison 11 is less likely to be pushed into the sub-cavity 3 by the air pressure blown. It is not necessary to employ a means for positioning the end surface of the core portion 4 at the boundary between the main cavity 2 and the sub cavity 3 at the time of blow molding. (Embodiment 3) In Embodiment 2, the boundary between the main cavity 2 and the sub cavity 3 is communicated with the outer peripheral portion of the core portion 4 during blow molding. Therefore, when air is blown into the parison 11 at the time of blow molding or when the communicating portion of the outer peripheral portion of the core portion 4 is large, the parison 11 is pushed into the sub-cavity 3 by the blown air pressure. This embodiment deals with such a case.

As shown in FIG. 11, the boundary surface communicating with the main cavity 2 of the sub-cavity has a wall surface formed by the core portion 4 and the cylindrical second core portion 10. In the blow molding process,
The parison 11 is introduced into the main cavity 2 and blow-molded as in the second embodiment to form a blow-molded body 16 as shown in FIG. Next, in the communication hole forming step, as shown in FIG.
As shown in FIG. 5, the core portion 4 is moved to break through the wall of the blow molded body 16 to form a communication hole. In the injection molding process,
As shown in FIG. 3, the second core portion 10 is retracted to form the space of the sub-cavity 3.

Then, a resin is injection-molded in the sub-cavity 3 to form an injection-molded body 15 and a blow-molded body 16 as shown in FIG.
A blow-molded article having the same opening as in Example 2 was formed by removing the mold by forming a blow-molded body in which the and were joined together. (Embodiment 4) The manufacturing method of Embodiment 1 is the same as that of Embodiment 1 except that the parison 11 is not pierced by the core portion 4 and is protruded inwardly to form the concave cylindrical portion 17 in the communication hole forming step. Was done. After the demolding, the tubular portion 17 was cut and removed with a heat cutter at the time of finishing the blow-molded product to form a communication port.

In the communication hole forming step after the injection molding step and the blow molding step of the first embodiment, as shown in FIG. On the other hand, the cylindrical portion 17 is formed. Then, by removing the blow-molded body 16 and cutting the cylindrical portion 17 at the time of finishing as shown in FIG. 14b, the opening edge surface 18 of the main body can be made smooth without post-processing.

Besides this, the parison 11 may be pierced to form a cylindrical portion. In this case, the protrusion of the core portion 4 may be before the parison 11 is solidified. (Fifth Embodiment) In the manufacturing method of the third embodiment, the tubular portion 17 is formed in the same manner as in the fourth embodiment, and the tubular portion 17 is cut and removed by a cutter at the time of finishing of the blow-molded body 16 after demolding. It is a method of forming the mouth.

In the sub-cavity 3, the second core 10 is positioned at the position of the main cavity 2 and the core portion 4 is projected into the main cavity 2 to perform blow molding, and the cylindrical portion 1 as shown in FIG.
Blow molding having a bottomed cylindrical portion 17 shown in FIG. 16b by forming a sub-cavity 3 by retracting the core portion 4 from the second core portion 10 to form a sub-cavity 3. The body 16 is formed. Then, the mold is removed and FIG.
When the cylindrical portion 17 was cut by finishing as shown in c, a blow-molded product having an opening similar to that of Example 4 with a smooth opening edge surface 18 was obtained. (Embodiment 6) This manufacturing method is an example of an insert molded body in which the insert metal fitting 19 is arranged to reinforce the resin layer in the opening and the resin layer is provided around the insert metal fitting 19.

As shown in FIG. 17 a, the sub-cavity 3 is formed by inserting and arranging the sub-mold portion 9 that forms the boundary surface between the sub-cavity 3 and the main cavity 2 into the main cavity 2 of the mold 1. Inside the sub-cavity 3, a core portion 4 having a cylindrical insert metal fitting 19 having a collar 21 at one end mounted on the outer peripheral surface is arranged, and the sub-mold portion 9 and the collar 21 of the insert metal fitting 19 form a boundary between the main cavities. It is regulated. A resin is injected into the sub-cavity in the injection molding process as shown in FIG. 17b to form a tubular injection molded body 20. Next, the sub-mold portion 9 is removed, and the injection-molded body 20 has a wall surface side of the main cavity 2 and a flange 21 surface of the insert fitting 19 on the side surface 2 of the resin.
A part of 3 is fusion-bonded to the blow-molded body 16. An annular cut is provided on the mold wall surface of the main cavity 2 to facilitate fusion bonding.

In the blow molding step, the parison 11 is extruded into the main cavity 2 and air is blown into it to blow-mold the blow-molded body 16 onto the insert fitting 19 of the injection-molded body 20 and the side surface 23 of the resin as shown in FIG. 17c. Join and integrate. In the communication hole forming step, the core portion 4 is axially driven to break through the resin wall as in the first embodiment.
A hole communicating with the hollow hole of the injection-molded body 20 is formed, and FIG.
The resin is solidified in this state as shown in.

After the resin has solidified, the mold is removed to remove the sprue runner 6 and the like to obtain a blow-molded article having an opening having a hole communicating the internal space with the outside. (Embodiment 7) Here, the insert metal fitting of Embodiment 6 was used to first form the blow-molded body 16 as in Embodiment 3, and then injection molding was carried out.

As shown in FIG. 18a, the interface of the opening of the main body is at the core 4 and the insert metal fitting 1 inserted in the core 4.
9 and the second core part 10 regulate. The insert fitting 19 is mounted on and supported by the core portion 4. Next, the parison 11 is extruded, and air is blown from the blow pin to perform blow molding to form the blow molded body 16.

In the step of forming the communication hole, as shown in FIG. 18b, the core portion 4 is axially driven to break through the wall surface of the blow-molded body 16 to form a hole for communication to the external space. At this time, the second core portion 10 and the insert fitting 19 are in contact with the wall surface of the blow-molded body 16 and hold the boundary surface. Next in FIG.
As shown in 8c, the second core portion 10 is moved backward to form a sub-cavity. At this time, one end surface of the sub-cavity is arranged so as to form an interface capable of being joined to the flange 21 surface of the insert fitting 19 and the parison 11.

In the injection molding process, injection molding is performed as in the third embodiment. At this time, the injection molded body 15 is changed to the blow molded body 16
The injection molded body 15 is formed by joining and fusing at the boundary surface 23 of the insert metal fitting 19 inside the collar 21. On the other hand, the core portion 4 is held in a state of being inserted into the blow molded body 16. The solidified molded product was demolded to obtain a blow molded product having an opening having a hole communicating with the joint wall surface as in the case of Example 6.

[0032]

According to the manufacturing method of the present invention, when molding another molded body into the molded body previously molded in the molding die, the core portion is pushed into the joint surface to form the hole, so that the main body portion is formed. It is possible to easily form a molded product in which the internal space forms a hole that communicates with the outside and is integrated with the opening. Therefore, the obtained molded product does not need to be punched in the post-processing as in the case of the conventional method, the process can be shortened, and the defect due to the remaining chips generated during the post-processing can be prevented.

[Brief description of drawings]

FIG. 1 is a schematic side view of a mold used in Examples.

FIG. 2 is a schematic view of a divided surface of a mold.

FIG. 3 is a schematic diagram of one side illustrating a mold of Example 1.

FIG. 4 is a schematic diagram of one half surface for explaining the injection molding process of the first embodiment.

FIG. 5 is a schematic view of one half surface when the core die is removed after the injection molding process of the first embodiment.

FIG. 6 is a schematic diagram of one half surface for explaining the start of the blow molding process of the first embodiment.

FIG. 7 is a schematic diagram of one half surface for explaining a blow molding process of Example 1.

FIG. 8 is a schematic diagram of one half surface for explaining a communication hole forming step of the first embodiment.

FIG. 9 is a schematic view of one half surface of one side for explaining the mold of the second embodiment.

FIG. 10 is a schematic diagram of one half surface for explaining a blow molding process of Example 2.

FIG. 11 is a schematic diagram of one half surface for explaining a blow molding process of Example 3.

FIG. 12 is a schematic diagram of one half surface for explaining a communicating hole forming step of the third embodiment.

FIG. 13 is a schematic diagram of one half surface for explaining formation of a sub-cavity of the third embodiment.

FIG. 14 is a schematic diagram of one half surface for explaining the injection molding process of the third embodiment.

FIG. 15a is a schematic diagram of one half surface for explaining a communication hole forming step of the fourth embodiment. FIG. 15b is a schematic view of one half surface for explaining the shape of the communicating hole of the molded body of Example 4.

FIG. 16a is a schematic view of one half surface for explaining the start of the injection molding process of Example 5. FIG. 16b is a schematic view of one half surface for explaining the injection molding process of the fifth embodiment.

FIG. 17a is a schematic diagram of one half surface for explaining a mold and an insert fitting of Example 6; FIG. 17b shows Example 6
FIG. 3 is a schematic view of one half surface for explaining the injection molding process of FIG. Figure 1
7c is a schematic view of one half surface for explaining the blow molding process of Example 6. FIG. FIG. 17d is a schematic diagram of one half surface for explaining the communicating hole forming step of the sixth embodiment.

FIG. 18a is a schematic diagram of one half surface for explaining a blow molding process of Example 7. FIG. 18b is a schematic view of one half surface for explaining the communicating hole forming step of the seventh embodiment. Figure 18c
FIG. 10 is a schematic view of one half surface for explaining the relationship between the insert fitting and the second core portion before the injection molding process of the seventh embodiment. FIG.
d is a schematic view of one half surface for explaining the relationship between the insert metal fitting and the second core portion after the injection molding process of the seventh embodiment.

[Explanation of symbols]

1 mold, 2 main cavity, 3 sub cavity,
4 core parts, 5 drive parts, 6 spool runners,
7 ... Split mold surface, 8 Movable mold, 9 ... Sub mold part, 10 ... Second core part, 11 ... Parison, 12 ... Blow pin, 1
3 ... Blow molding machine, 14 ... Injection molding machine, 15, 20
Injection molded body, 16 blow molded body, 17 bottomed cylindrical portion, 18 opening cut surface, 19 insert metal fitting, 2
1 Tsuba of insert metal fittings, 23 Joint surface of injection molded body with blow molded body

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[Procedure amendment]

[Submission date] March 12, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] Fig. 16

[Correction method] Change

[Correction content]

FIG. 16a is a schematic view of one half surface for explaining the start of the injection molding process of Example 5. FIG. 16b is a schematic view of one half surface for explaining the injection molding process of the fifth embodiment. FIG.
c is a schematic view of one plane after demolding the molded body of Example 5.
is there.

Claims (3)

[Claims] 1. A method for producing a blow-molded product having an opening, which is composed of an injection-molded opening communicating with an inner space and the outside, and a blow-molded main body integrally joined to the opening. And defining a boundary between a main cavity forming an outer peripheral surface of the main body portion, a base mold having a sub-cavity communicating with the main cavity forming an outer peripheral surface of the opening, and a sub-cavity of the base mold portion. A molding die comprising a sub-mold portion and a core portion that is held in the base portion so as to be movable in the axial direction relative to each other and forms a hole for the opening. The injection molding step of forming the injection molded body of the opening by injection molding the resin, and removing the sub mold part from the injection molded body, and then introducing the parison into the main cavity to introduce the parison into the parison. Blow air to make contact with the injection molded body And a blow molding step of forming a blow molded body forming the main body, and a communication hole forming step of forming a hole in the wall surface of the blow molded body to communicate the internal space with the outside. For manufacturing a blow-molded product having an opening for forming. 2. A method for producing a blow-molded article having an opening, which comprises an injection-molded opening communicating with an internal space and the outside and a blow-molded main body integrally joined to the opening. And a base part having a main cavity forming the outer peripheral surface of the main body part, a sub-cavity communicating with the main cavity forming the outer peripheral surface of the opening, and a core part forming the hole of the opening. A blow molding step of using a mold to introduce a parison into the main cavity of the base mold to blow air into the parison to form a blow molded body that constitutes the main body, and the core after the blow molding. A step of forming a hole in the wall surface of the blow-molded body by relatively moving in the axial direction to communicate the internal space with the outside, and in the sub-cavity with the core portion arranged in the sub-cavity. Injection molding resin to blow An injection-molding step of forming an injection-molded body which forms an opening integrated with the blow-molded body while being brought into contact with and joined to the molded body, and one of the steps is performed first and the other step is subsequently performed. A method for producing a blow molded product having an opening characterized by the above. 3. An injection-molded opening for communicating the internal space with the outside and the blow-molded opening are integrally joined to each other to form a central hole communicating with the opening and projecting into the internal space. A blow molding product having an opening portion for communicating an internal space formed by cutting the tubular portion of a blow-molded product composed of a main body portion having a tubular portion with a cutter and an outside. -Molded products.