JPH05220787A - Mold structure for molding hollow molded products - Google Patents

Abstract

PURPOSE:To mold a hollow molded form having a hat-shaped section equipped with a hollow chamber at an upper side and a flanged protrusion at a lower end peripheral edge by forming a connected part of an upper divided body held by a fixed die with an open bottom face and a lower divided body held by a movable die on the fixed die at predetermined distances from divided faces of the dies. CONSTITUTION:A fixed die 1 and a movable die 2 mold an upper divided body 6 and a lower divided body 8 of a hollow molded form P by first injection at a time. Thereafter, the divided bodies 6 and 8 are connected by the movement of the movable die 2 so as to mold the hollow molded form P. Here, the connecting part of the divided bodies 6 and 8 is formed on the fixed die 1 at predetermined distances from divided faces A of the dies. Thus, at second molding, melted resin can be prevented from flowing in a flanged protrusion on the lower divided body from the connected part of the divided bodies, so that the hollow molded form having a hollow chamber formed on the upper side and the flanged protrusion on the lower end peripheral edge can be molded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding structure for a hollow molded product in which each divided product of a hollow molded product is individually molded by primary injection and then these divided products are joined by secondary injection. It is a thing.

[0002]

2. Description of the Related Art Conventionally, in general, a hollow molded article having a hollow chamber is formed by primary molding two divided bodies obtained by splitting the hollow molded article into the same mold, and thereafter moving the movable mold to move the hollow mold The divided bodies are superposed, and in this state, they are joined together by secondary forming to form the pieces.

Further, as a mold for molding the above hollow molded article, as disclosed in Japanese Patent Laid-Open No. 62-87315, a mold having a sprue and a runner as a molten resin supply passage is provided. Also, as disclosed in Japanese Patent Application No. 3-204208, one having a hot runner as a molten resin supply path has been proposed, and all of these molds have a joining portion of each divided body. Is formed on the mold-splitting surface, which enables abutting and joining of the respective joining sites during the secondary injection.

[0004]

However, as in the prior art, a mold having a sprue and a runner, or a hot runner, and molding a hollow molded product by joining each divided body has a problem in forming in the secondary molding. For the reason, the shape of each divided body formed by the primary forming is limited to the box shape. Therefore, the shape of the hollow molded product to be finally molded is limited only to the one having the hollow chamber,
For example, a cylinder head cover with a baffle plate, which has a hollow chamber on the upper side and has a flange-shaped projection for mounting on the outer peripheral edge of the lower end, has a hat-shaped cross section, and is a hollow molded product. It has a problem that it cannot be molded as.

In the case where one of the divided bodies to be primarily formed by the above-mentioned mold has a brim-shaped projection on the outer peripheral edge of the lower end, the joining portion is located on the molding surface. Therefore, a hollow chamber is formed above the brim-shaped protrusion during the secondary molding. Therefore, the molten resin for secondary molding flows into the hollow chamber from the joint site,
As a result, the hollow molded article cannot be molded into a desired shape.

[0006]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the molding die structure for a hollow-molded article according to claim 1 of the present invention takes the following means.

That is, after each divided body of the hollow molded product is molded between the fixed die and the movable die by the primary injection, the divided body is held in each die and the movable die is moved to divide each divided body. A structure for molding a hollow molded article in which the bodies are placed on top of each other, and then the divided bodies are joined by secondary injection to form a hollow chamber therebetween, wherein the divided bodies are An upper split body that is held by a fixed die and has a lower surface opened, and a lower split body that is held by the movable die and has a brim-shaped projection formed on the outer peripheral edge of the lower end to have a hat-shaped cross section.
The joint portion of each of these divided bodies is formed on the fixed mold side with a predetermined distance from the mold splitting surface.

Further, the molding die structure for a hollow molded article according to claim 2 is the same as the molding die structure for a hollow molded article according to claim 1, wherein the following measures are taken.

That is, the fixed die is formed with a convex portion for forming a groove portion on the outer surface of the lower divided body by the primary injection.
In addition, the groove portion of the lower divided body forms a supply path for supplying the molten resin to the joint portion of each divided body at the time of secondary injection,
This molten resin is solidified and embedded in a predetermined outer surface shape.

[0010]

According to the molding die structure for a hollow molded product according to claim 1, an upper divided body having an open lower surface and a lower divided body having a hat-shaped cross section provided with a flange-shaped projection on the outer peripheral edge of the lower end. And are molded between the fixed mold and the movable mold by primary injection. Then, the movable die is moved while the upper die is held by the fixed die and the lower die is held by the movable die, and the upper and lower divided bodies are superposed on each other. Then, the molten resin is supplied to the joint portion of each divided body by the secondary injection to join the divided bodies. By the way, since the joint portion of each of the above-mentioned divided bodies is formed on the fixed mold side at a predetermined distance from the mold splitting surface, respectively, the joint portion and the lower divided body side in the state where the respective divided bodies are superposed on each other. The brim-shaped protrusion is in a state of being blocked by the fixed mold. Therefore, there is no fear that the molten resin for secondary molding will flow from the joining site into the flange-shaped protrusion on the lower split body side, and as a result, the hollow chamber is formed on the upper side and the flange-shaped protrusion is formed on the outer peripheral edge of the lower end. It becomes possible to form a hollow molded article having

Further, according to the molding die structure of the hollow molding product according to the second aspect, by forming the convex portion on the fixed die, the groove portion is provided on the outer surface of the lower divided body by the primary injection. .. And
At the time of the secondary injection, this groove portion supplies molten resin to the joint portion of each divided body, and then is solidified to fill the grooved portion with a predetermined outer surface shape. Therefore, it is possible to form a molten resin supply path that supplies the molten resin in two directions for molding each divided body during the primary injection and shuts off one supply during the secondary injection with a simple configuration.

[0012]

【Example】

[Embodiment 1] FIG. 1 through FIG.
The explanation is based on the following.

As shown in FIG. 1, the mold according to this embodiment is a fixed mold 1 in which a resin supply port 10a of an injection machine 10 is arranged.
And a movable die 2 capable of opening / closing in the left / right direction and sliding in the up / down direction, and configured as a die slide type die structure.

The fixed mold 1 is formed with a hot runner 3 having a heating means 4 such as a heater arranged on the outer periphery thereof. One end side of the hot runner 3 is communicated with the resin supply port 10a of the injection machine 10, while the hot runner 3 is divided into two in the middle so that each other end side is communicated with the first and second cavities 7 and 9 described later. The molten resin injected and injected from the injection machine 10 is supplied to each of the cavities 7 and 9 in a molten state. Further, an on-off valve 5 is provided in an intermediate path of the hot runner 3 on the second cavity 9 side, and the on-off valve 5 controls the supply of the molten resin to the second cavity 9 by its opening / closing operation. It is like this.

Further, the fixed die 1 and the movable die 2 are adapted to be mutually die-molded with the die-splitting surface A as the center, and each die 1 and 2 in such die-mate state. On the upper side of the upper part of the hollow molded product, the upper split body 6
While a first cavity 7 for molding is formed, a second cavity 9 for molding the lower divided body 8 is formed on the lower side.

The first cavity 7 is formed in a concave shape on the mold dividing surface A of the fixed mold 1 to form the outer surface shape of the upper divided body 6, and the mold dividing surface A of the movable mold 2. A first female mold portion 2a which is formed in a convex shape to shape the inner surface shape of the upper divided body 6
And is formed by cooling and solidifying the molten resin between the first male mold portion 1a and the first female mold portion 2a.
A box-shaped upper divided body 6 having an opened lower surface is formed. The above-mentioned first female mold portion 2a is the lower edge portion of the entire peripheral wall of the box-shaped upper divided body 6 (joint portion with the lower divided body 8).
Is formed at a position spaced a predetermined distance from the mold-splitting surface A, and the shape thereof is formed in a stepwise manner, so that it is located outside the lower edge of the entire peripheral wall of the upper divided body 6. The joining groove portion 6a is formed in a continuous shape.

On the other hand, the second cavity 9 is formed by a second male mold part 1b for molding the outer surface shape of the lower divided body 8 and a second female mold part 2b for molding the inner surface shape of the lower divided body 8. A lower split body having a hat-shaped cross section in which a flange-shaped protrusion 8a is provided on the lower peripheral edge of the lower end by cooling and solidifying the molten resin between the second male mold portion 1b and the second female mold portion 2b. 8 is to be molded.

As shown in FIG. 2, the second male mold portion 1b has a convex region formed in a convex shape on the mold cutting surface A of the fixed mold 1 and a mold of the fixed mold 1 in a continuous shape from the convex region. The split surface A has a concave region formed in a concave shape, the convex region forms a lower outer surface including the collar-shaped protrusion 8a of the lower split body 8, and the concave region forms the upper surface of the lower split body 8. It is adapted to mold the upper outer surface including. On the other hand, the second female mold portion 2b corresponds to the above-mentioned second male mold portion 1b, and has a concave area formed in a concave shape on the mold dividing surface A of the movable mold 2 and a continuous movable shape from this concave area. 2 has a convex region formed in a convex shape on the mold dividing surface A, and the concave region forms the lower outer surface including the collar-shaped protrusion 8a of the lower divided body 8, and the convex region is the lower divided body. The upper outer surface including the upper surface of 8 is molded.

In the second male mold portion 1b, the portion for molding the upper peripheral edge portion (joint portion with the upper divided body 6) of the lower divided body 8 having a hat-shaped cross section is from the mold dividing surface A. It is formed at a position separated by a predetermined distance, and the shape thereof is formed stepwise so that the joining groove 8b can be formed in a continuous shape on the outer peripheral edge of the upper surface of the lower divided body 8. Is becoming

A molding process of a hollow molded product by the fixed mold 1 and the movable mold 2 which compose the main mold in the above structure will be described below.

First, as shown in FIG. 1, the fixed mold 1 and the movable mold 2 are matched with each other with the opening / closing valve 5 opened. Next, the molten resin is injected and injected (primary injection) from the injection machine 10 to fill the molten resin into the first and second cavities 7 and 9 formed between the molds 1 and 2, and then, , The molten resin is cooled and solidified to form the upper and lower divided bodies 6.
8 is primarily molded.

Next, the upper split body 6 molded in the first cavity 7 is attached to the first male die portion 1a of the fixed die 1, and
The lower split body 8 molded in the second cavity 9 is moved to the movable mold 2
The second female mold portion 2b of the
The movable mold 2 is sequentially moved in each direction of mold opening, sliding upward, and mold clamping by a mold moving device (not shown). As a result, the lower edge portion of the entire peripheral wall of the upper divided body 6 and the outer peripheral edge portion of the upper surface of the lower divided body 8 are in a state of abutment as shown in FIG. The joining groove portion 6a of the body 6 and the joining groove portion 8b of the lower divided body 8 form a series of joining groove portions communicating with the hot runner 3.

Next, with the on-off valve 5 closed, the injection machine 1
The secondary injection is performed by 0, and as shown in FIG. 4, the joining groove formed by the joining groove 6a and the joining groove 8b is filled with the molten resin. Then, the molten resin filled in the joining groove portion is cooled and solidified to join the upper divided body 6 and the lower divided body 8 to form a hollow chamber R on the upper side as shown in FIG. Then, the (secondary) molding of the desired hollow molded product P in which the collar-shaped protrusion 8a is provided on the outer peripheral edge of the lower end is completed.

As described above, in the fixed mold 1 and the movable mold 2 which are the molds of this embodiment, the upper split body 6 and the lower split body 8 of the hollow molded product P are simultaneously molded by primary injection, After that, movable type 2
By moving the above-mentioned divided bodies 6 and 8, the divided bodies 6 and 8 are overlapped, and in this state, the divided bodies 6 and 8 are joined to form a desired hollow molded product P.

By the way, the joint portions of the respective divided bodies 6 and 8 as described above are formed on the fixed mold 1 side at a predetermined distance from the mold dividing surface A, respectively. Therefore, the upper divided body 6 is
Like the conventional split body, the lower split body 8 is formed into a box shape with an open lower surface, while the lower split body 8 has a brim-shaped protrusion 8a at the outer peripheral edge of the lower end.
Can be formed into a hat-shaped cross-section, and as a result, a hollow chamber R is formed on the upper side and a collar-shaped projection 8a is provided on the outer peripheral edge of the lower end to form a hat-shaped cross-section. It enables the molding of product P.

[Second Embodiment] The following will describe another embodiment of the present invention with reference to FIGS. 6 to 8. Since the hollow molded product molded by the mold of the second embodiment is the same as that molded by the mold of the first embodiment, for convenience of description, each component forming the hollow molded product will be described. The same reference numerals are used and FIG. 5 is used again.

As shown in FIG. 6, the mold according to this embodiment has a resin supply port 20a of the injection machine 20 as in the first embodiment.
Is provided, and a movable die 12 capable of opening / closing in the left / right direction and sliding in the up / down direction, and is configured as a die slide type die structure. The fixed mold 11 is formed with a sprue 14 having one end communicating with the resin supply port 20a of the injector 20 and the other end communicating with a runner 13 described later.

The fixed mold 11 and the movable mold 12 are
Each of them is designed to be fitted to each other around the mold cutting surface A.
On the upper side of 12, a first cavity 17 for molding the upper divided body 6 obtained by vertically dividing the hollow molded product into two is formed, while on the lower side, for molding the lower divided body 8. The second cavity 19 is formed. The movable die 12 is formed with a runner 13 communicating with the above-mentioned sprue 14 along the way.
The two ends of the resin are communicated with the cavities 17 and 19, so that the molten resin from the sprue 14 is transferred to the cavities 1 and 19.
It will be supplied on July 19th.

The first cavity 17 is formed on the mold dividing surface A of the fixed mold 11 in a concave shape to mold the outer surface shape of the upper divided body 6, and the mold dividing surface A of the movable mold 12. And a first female mold part 12a which is formed in a convex shape to mold the inner surface shape of the upper divided body 6, and these first male mold parts 1 are formed.
By cooling and solidifying the molten resin between 1a and the first female mold portion 12a, a box-shaped upper divided body 6 having an opened lower surface is formed. In addition, the above-mentioned first female part 12
In a, a portion for molding the lower edge portion of the entire peripheral wall (joint portion with the lower divided body 8) of the box-shaped upper divided body 6 is formed at a position spaced from the mold dividing surface A by a predetermined distance. At the same time, since the shape thereof is formed in a step shape, the joining groove 6a is formed in a continuous shape outside the lower edge of the entire peripheral wall of the upper divided body 6.

On the other hand, the second cavity 19 is fixed mold 11
A second male mold part 11b which is formed in a concave shape on the mold dividing surface A and molds the outer surface shape of the lower split body 8 and a second female mold part 12b which molds the inner surface shape of the lower split body 8. A lower split body having a hat-shaped cross section in which a flange-shaped protrusion 8a is provided on the lower peripheral edge of the lower end by cooling and solidifying the molten resin between the second male mold portion 11b and the second female mold portion 12b. 8 is to be molded.

In the second male mold portion 11b, a portion for molding the upper peripheral edge portion (joint portion with the upper divided body 6) of the lower divided body 8 having a hat-shaped cross section has a predetermined distance from the mold dividing surface A. Is formed at the position where the is placed, and the shape thereof is formed in a stepwise manner, so that the joining groove portion 8b is formed in a continuous shape on the outer peripheral edge of the upper surface of the lower divided body 8. ..

The second female mold part 12b has a concave area formed in a concave shape on the mold cutting surface A of the movable mold 2, and a convex shape formed on the mold dividing surface A of the movable mold 2 in a continuous shape from the concave area. A concave inner surface of the lower divided body 8 including the flange-shaped projection 8a, and a convex area of the lower divided body 8 including an upper surface of the lower divided body 8. It has become.

Further, the fixed mold 11 of this embodiment has a second
A single convex portion 1 extending from the lower end of the male mold portion 11b to the mold dividing surface A
1c is formed, and the movable die 12 is provided with a concave portion 12c that fits with the lower end side of the convex portion 11c formed on the mold dividing surface A of the fixed die 11. As a result, the convex portion 11c of the second male mold portion 11b is, as shown in FIG. 7, during the molding of the lower divided body 8, the joining groove portion 8b of the lower divided body 8.
A single grooved groove portion 8c is provided from to the collar-shaped protrusion portion 8a. On the other hand, the concave portion 12c of the second female die portion 12b is arranged in communication with the other end side of the sprue 14 by the movement of the movable die 12 accompanying the secondary injection as described later,
A runner for supplying the molten resin is configured.

A molding process of the hollow molded product by the fixed mold 11 and the movable mold 12 which compose the main mold in the above structure will be described below.

First, in a state where the fixed mold 11 and the movable mold 12 are matched with each other as shown in FIG. 6, a molten resin is injected and injected (primary injection) from the injection machine 20, and the sprue 14 and the runner 13 are used. The molten resin is filled in both cavities 17 and 19, and then the molten resin is cooled and solidified to primarily mold the upper and lower divided bodies 6 and 8.

Next, the upper divided body 6 molded in the first cavity 17 is attached to the first male mold portion 11a of the fixed mold 11,
Further, the lower divided bodies 8 molded in the second cavity 19 are respectively held by the second female mold portion 12b of the movable mold 12, and in this state, the movable mold 12 is moved by a mold moving device (not shown).
Is sequentially moved in each direction of mold opening, upward sliding, and mold clamping. At this time, the unnecessary resin portion cooled and solidified in the sprue 14 and the runner 13 is cut and removed manually or by an apparatus.

As a result, the lower edge portion of the entire peripheral wall of the upper divided body 6 and the outer peripheral edge portion of the upper surface of the lower divided body 8 are in an abutting state as shown in FIG. Further, in such an abutting portion, a series of joining groove portions is formed by the joining groove portions 6a of the upper divided body 6 and the joining groove portions 8b of the lower divided body 8. This joining groove portion is the groove portion 8c of the lower divided body 8.
And is in communication with the sprue 14 through the recess 12c of the movable die 12.

Next, the secondary injection is performed by the injection machine 10, so that the molten resin is passed through the sprue 14, the concave portion 12c of the movable die 12, and the groove portion 8c of the lower divided body 8 to the above-mentioned joining groove portion. Fill. Then, the molten resin filled in the joining groove portion is cooled and solidified to join the upper divided body 6 and the lower divided body 8 to form a hollow chamber R on the upper side as shown in FIG. And the collar-shaped projection 8a on the outer peripheral edge of the lower end
The (secondary) molding of the desired hollow molded product P molded by is completed. In the joining of the upper divided body 6 and the lower divided body 8 as described above, the groove portion 8c of the lower divided body 8 forming the molten resin supply path is formed by cooling and solidifying the molten resin inside. ,
It is to be filled with a desired outer surface shape.

As described above, the fixed mold 11 and the movable mold 12 which are the molds of this embodiment are similar to the molds 1 and 2 of the first embodiment, and the hollow mold product P is formed by the primary injection. By simultaneously molding the divided body 6 and the lower divided body 8, and then moving the movable mold 2 to overlap the divided bodies 6 and 8 described above, and in this state, by joining the divided bodies 6 and 8. It is possible to mold a hollow molded product P having a hat-shaped cross section as a whole.

By the way, the second male part 1 of the fixed mold 11
1b and the second female portion 12b of the movable die 12 are respectively formed with a convex portion 11c and a concave portion 12c which are fitted to each other in a mold clamping state, and the convex portion 11c is a lower split body. 8
At the time of molding, a single grooved portion 8c is provided from the joining grooved portion 8b of the lower divided body 8 to the brim-shaped protrusion 8a, while the recessed portion 12c constitutes a molten resin supply passage associated with the secondary injection. It is supposed to do.

Therefore, in the first embodiment, the hot runner 3 having the open / close valve 5 is provided so that the molten resin is not supplied to the second male mold portion 1b side of the fixed mold 1 during the secondary injection. However, in the second embodiment, the supply of the molten resin to the second male mold portion 1b side can be cut off without providing the on-off valve 5 and the hot runner 3, and as a result, the injection machine 20 Therefore, the structure of the supply passage (the sprue 14 and the runner 13) for supplying the molten resin to the cavities 17 and 19 can be simplified.

The first and second embodiments described above do not limit the present invention, and various modifications can be made within the scope of the present invention. For example, the shape of the joining portion between the upper divided body 6 and the lower divided body 8 is not particularly limited, and as shown in FIG. 9, the joining groove portion 6a provided on the upper divided body 6 side,
Joining the joining projections 8d provided on the lower divided body 8 side, and, as shown in FIG. 10, providing the joining groove portions 8b provided on the lower divided body 8 side and the joining grooved portions 8b provided on the upper divided body 6 side. Bonding protrusion 6
It is also possible to join with b.

[0043]

As described above, in the molding die structure for a hollow molded product according to claim 1 of the present invention, each divided body of the hollow molded product is molded between the fixed mold and the movable mold by the primary injection. After that, while holding these divided bodies in each mold and moving the movable die, the divided bodies are put on top of each other, and then the divided bodies are joined by secondary injection, and the hollow body is placed between them. A mold structure for molding a hollow molded product forming a chamber, wherein each of the above-mentioned divided bodies is held by a fixed die and an upper divided body whose lower surface is opened, and a movable die, and an outer peripheral edge of a lower end. It is composed of a lower split body having a hat-shaped cross-section with a brim-shaped projection formed on the section, and the joint portions of these split bodies are formed on the fixed mold side at a predetermined distance from the mold splitting surface. It has a structure.

As a result, when the box-shaped upper divided body having the opened lower surface and the lower divided body having the hat-shaped cross section provided with the flange-shaped projection on the outer peripheral edge of the lower end are secondarily formed, each divided body is formed. Since it is possible to prevent the molten resin from flowing from the joining portion to the flange-shaped projection on the lower split body side, as a result, a hollow chamber is formed on the upper side and the flange-shaped projection is provided on the outer peripheral edge of the lower end. It enables the molding of hollow molded products. Therefore, in the case of molding a cylinder head cover including a baffle plate, the baffle plate can be integrally molded with the cover, so that the work of assembling the baffle plate can be eliminated and the productivity is improved. There is an effect that can be done.

Further, the molding die structure for a hollow molded article according to claim 2 is the same as the molding die structure for a hollow molded article according to claim 1, wherein the fixed die has an outer surface of the lower divided body by primary injection. The groove portion of the lower divided body serves as a supply path for supplying the molten resin to the joint portion of each divided body at the time of secondary injection. The molten resin is solidified and embedded in a predetermined outer surface shape.

Thus, even when forming a hollow chamber on the upper side and forming a hollow molded product having a flange-shaped projection on the outer peripheral edge of the lower end, a special device such as an on-off valve and a hot runner is provided. Therefore, it is possible to simplify the supply path of the molten resin, and it is possible to significantly reduce the cost.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a die matching state during primary injection of a fixed die and a movable die according to an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view showing a second male die portion formed on the fixed die and a second female die portion formed on the movable die.

FIG. 3 is a vertical cross-sectional view showing a mold matching state of the fixed mold and the movable mold at the time of secondary injection.

FIG. 4 is a vertical cross-sectional view showing a state in which a molten resin is filled between the divided bodies that are primarily molded by the fixed mold and the movable mold.

FIG. 5 is a vertical cross-sectional view showing a hollow molded article formed by joining the above-mentioned divided bodies.

FIG. 6 is a vertical cross-sectional view showing a die matching state during primary injection of a fixed die and a movable die according to another embodiment of the present invention.

FIG. 7 is a perspective view showing a lower split body in which groove portions are provided by the fixed convex portions.

FIG. 8 is a vertical cross-sectional view showing a mold matching state of the fixed mold and the movable mold at the time of secondary injection.

FIG. 9 is a vertical cross-sectional view showing a hollow molded article in which a joining portion is provided near the upper divided body.

FIG. 10 is a vertical cross-sectional view showing a hollow molded article in which a joint portion is provided near the lower divided body.

[Explanation of symbols]

 1 ・ 11 Fixed type 2 ・ 12 Movable type 6 Upper divided body 6a ・ 8b Joining groove section 8 Lower divided body 8a Collar-shaped protrusion 8c Groove section P Hollow molded product R Hollow chamber

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shozo Nishida 1-6-7 Funakoshi Minami, Aki-ku, Hiroshima City, Hiroshima Prefecture Japan Steel Works Hiroshima Works (72) Inventor Shinji Kasami Hachimotomatsu, Higashihiroshima City, Hiroshima Prefecture No. 175, Odaira, Omachi, Daikyo Co., Ltd.

Claims (2)

[Claims] 1. A method of molding each divided body of a hollow molded article between a fixed die and a movable die by primary injection, holding these divided bodies in each die, and moving the movable die to make each division. A structure for molding a hollow molded article in which the bodies are superposed on each other, and then the divided bodies are joined by secondary injection to form a hollow chamber therebetween, wherein each of the divided bodies is An upper split body which is held by a fixed die and whose lower surface is opened; and a lower split body which is held by the movable die and has a brim-shaped projection formed on the outer peripheral edge of the lower end to form a hat-shaped cross section. A molding die structure for a hollow molded article, wherein a joint portion of each divided body is formed on a fixed die side which is spaced a predetermined distance from a mold splitting surface. 2. The fixed die is formed with a convex portion for forming a groove portion on the outer surface of the lower divided body by primary injection, and
The groove portion of the lower divided body serves as a supply path for supplying the molten resin to the joint portion of each divided body at the time of secondary injection, and the molten resin is solidified and filled in a predetermined outer surface shape. The mold structure for molding a hollow molded article according to claim 1.